forensic science test 2

detection and visualization of fingerprints

- fingerprints can be left in a wide range of places at a crime scene so fingerprint technicians spend good amount of time searching to recover them. - patent and plastic are the easiest to discover because they can be scene without any help '-the challenge is to discovering and visualizing latent prints - chemical and physical methods have been developed and revised throughout the years - the method used to detect latent prints will depend on the surface - locating prints on non-absorbing surfaces ( glass, or painted wood) can be done using Uv light non-pourus surfaces can de dusted.

area of convergence

- in a number of bloodstains area of convergence can be determined by drawing lines from leading edge of stains through the long axis - area of convergence helps to locate the origins of the bloodstain

history of fingerprints sir francis galton

- published book on finger prints - categories of fingerprints loops arches and whirls - he said finger prints where unique and are unchanged throughout life.

fluorescein

- reagent that also emits light when exposed to an oxidant and heme - this reagent undergoes flurescene rather than chemiluminescence -it applied to suspect blood evidence along with hydrogen peroxide - an outside light ( strong short wave of length) must be applied to induce fluorescene.

seminal fluid

- seminal fluid is a mixture of cells, sperm and a variety of organic and inorganic materials - produced in male seminal vesicles, prostate and Cowper's glands - some males have low sperm counts or no sperm ( aspermic) - seminal fluid contains large concentrations of seminal acid phosphate - SAP is what presumptive tests target.

origin/ anatomy of fingerprints

- the purpose of fingerprints and friction ridges is to provide a textured surface to grip and hold objects fingerprints arise from the dermal papillac which is found between the epidermis ( outer layer of the skin) and the dermis( inner most layer of skin) -fingerprints ridges begain forming the 8th week of gestation and are fully formed by the 17th week fingerprints dont change after this. -perspiration released from sweat glands exists through pores - perspiration contains skin cells, proteins ,and fats that are deposited when a finger touches a surface

preliminary tests for semen

- the seminal acid phosphate (SAP) test has emerged as the only acceptable presumption test for seminal fluid -Brentamine Fast Blue B reagent is major for seminal fluid - a positive result shows an intense purple color with in 2 minutes - draw back the test is carcinogenic and must be handled with care

why are they crucial

- usually no witness to sexual assault crimes, so its crucial to associate physical evidence with the suspect - most locate biological evidence in order to DNA type. - must confirm the type of evidence to establish that such a crime has occurred.

Sir Alec Jeffreys

-british geneticist - developed DNA fingerprinting in 1985 - saw that certain type of DNA sequences repeated themselves -foumnd that there where variations amoung these in the human population -jefferese then developed a method to determine the length of these repeating fragments from tissue -defined them as variable number tandem repeats (vntr) became know as restrictions fragment length polymorphism (relp) analysts.

Passive Stains

-created sue to force of gravity acting on the blood -types of passive stains 1. Vertical blood drops ( blood dropping at 90 degress to the surface) 2. transfer stains ( blood on an object that connects another object and leaves a blood pattern such asd swipes, footprints) 3. flow( large pool of blood moving down a wall . or incline) 4. large volume( blood existing in mass from a person or animal)

Microbiology forensics

-relatively new and rapidly evolving scientific discipline in forensic science - field created as a result of 2001 anthrax attacks - this event brought awareness to the countrys lack of preparedness in characterizing bacteria used for bioterrorism purposes - before this attack the center for disease control relied on syndrome surveillance syndrome surveillance: using clinical features that are discernible before diagnosis is confirmed.

ACE-V method

1. Analysis: examine and analyze all variables 2. comparison: introduce the known print 3. evaluation: peer reviewed most important

2 major types of testing

1. luminol 2. Fluorescein - preliminary test - use fluorescein to locate trace amount of blood at a crime scene.

other test for seman

1. prostate specific antigen - because some males have low sperm count or no sperm at all, seminal fluid may be confirmed if the stain reacts postivly for the presence of seminal acid phosphate and if prostate-specific antigen ( PSA or p3o) is identified - a test for psa was developed in 1999 and is still used today.

three of the most important bioloigical fluid besides blood are

1. seminal fluid 2. vaginal secretion 3. saliva - these are important evidence in criminal sexual conduct

handwriting comparisons

1. the presence of sufficient unique characteristics in the questioned document 2. proper collection of exemplars ( writing example from suspect) - proper collection of examplars is important for accurate comparison - what should be considered - writing instrument - paper - physical condition - mental condition

important dates

1892 - first convict to be convicted on finger print 1904- convict fingerprints from Leavenworth & another prison went into FBI files 1934- number of fingerprint cards in FBI files reached 10 million 1959- roy harbor of candian mountain police used ACE method 1959- sgt david ashhaugh used ACE-V method within friction ridge feild and population 1973- first phase of automated criminal history search 1976- first afis in testing 1996- FBI encourages child fingerprinting incase they go missing 1999- FBI international automated fingerprints identification system

FBI quality guide lines

A t a minimum - a description of evidence - examined listing of local analysis - description of the methodology -results and or conclusions - interpretative statement either -quantitative or qualitative

animal testing

A test animal ( usually a rabitt) is injected with human blood serum which contains antigens. - the animal immune system will recognize this as a foregin object and produce antibodies. - the animals blood is now an antiserum for human antigens and can be used to test for the presence of blood -animal serium is added to a suspected sample of human blood - if done in a test tube -> precipitin ring test - if done in solution or in gel -> ouchterlony double diffusion test if the blood is human, there will be a reaction between the antihuman antibodies in the antiserum and the human antigens in the blood.

BPA

An area of forenswic science that interprets the patterns seen in deposited blood and relates them to the actions that could have caused the pattern - it is growing feild of crime scene analysis - invaluable in crime scene reconstruction -can be used to provide evidence or exonerate suspect.

the innocence project

An organization staffed by lawyers and law students who reexamine cases and provide legal assistance to convicts when there is a probability that serious errors occurred in their prosecution. - founded by barry scheck in 1992 school of law in yeshiva university at new york - - where post coviction DNA typing could be used to prove claims of innocence types of cases taken: claims of ineffective counsel, crime lab scientist mistakes, cases with evidence based on pre-DNA typing blood analysis

Anthrax

Anthrax is a serious infection disease caused by gram-positive, rod-shaped bacteria know as bacillus anthracis -symptoms depend on the way it is contracted - inhalation anthrax: fever and chills, chest discomfort, shortness of breath, confusion or dizziness, cough, nausea, vomiting, or stomach pains cutaneous anthrax: skin blisters/ulcers

2001 anthrax attack

Anthrax was sent anonymous letters to news agencies in Florida and new york and a congressman's office building in Washington between sep 18, 2001 - oct 9, 2001 - letters contained a white powdery substance (anthrax spores) -became one of the largest epidemiological and criminal investigations in the united states deaths 5 injuries 17 - further analysis of the strain found it was ames strain on or 89 strain of anthrax. - found rare mutants which found a unique microbial print. - 4 stable mutations chosen - found isolates from labs in uk canada Sweden and usa -the army medical research institute was a match with the four - prepared in 1997 by bruce edwards lvins during his research on anthrax vaccines. - no charges filed against him - commited suicide in 2008 no arrest have been made in this attack -lead for forensic science to be better in fields of bioterrism

AFIS

Before the compute-ration system it was impossible for the enforcement to search vast data sets of 10 printed cards FBI and national institutes of standards and technology developed a standard format for storing prints - disadvantage the software developed made it difficult to share data among users of different systems - in 1999 the fbi integrates a new automated system called IAFIS - which can compare a persons fingerprints against a database counting millions of sets of prints - it can also search the database for a single print found at a crime scene.

analysis

Blood is a solution of various materials in water it's a suspension insoluble material carried through body of water -plasma liquid portion of blood 55% of it's volume -also contains cloting properties

packaging and collection of DNA

DNA can be rendered usless if not properly collected DNA can be collect from different sources ex. toothbrush, hat Only need trace DNA to get a match wear protective clothing to ward off diseases like aids also good to wear ppf to not get hair or dandruff on evidence change gloves frequently package in breathable container like paper bag if packaged in air tight container moister builds up and s=dstroyes evidence. collect examplar DNA collect know samples from inside cheak

serology

Def. the examination and identification of body fluid ex. blood and sperm serological evidence consists of blood or body fluid from sexual assault cases

definitions

Denaturation: mixture is heated close to boling causing strands to denature and becmoe single stranded annealing: temperature of mixture is lowered primers than add to one of each of the single strands DNA extension: a base (nucleotide) adds top first open position next to primer process is replaced until the new strand is complete - these steps occur in a machine called a thermoctycler in 32 cycles at 100% efficiency 1.07 billion copies of targeted DNA region are created.

DNA replication

Dna strands are separated - each single strand is used as a template to make a complementary strand - two identical DNA molecules are produced.

typewriters , photocopiers and printers.

Document examiners must know these iteams - docxuments created by these machines must be analyzed differently because printing from the same machine will produce very similar documents - some machines may develop characteristics which could individualize them type writers: figures may bend or chip and may cause flaws in certain areas photocopier individual markings may be deposited on the paper when copies are made ex. grabber marks , toner gaps printers: don't usually have characteristics because of modern technology doesn't have defected

questioning document

Handwritten analysts is only one are in document examination - charred/indented writing paper/ink analyst forgeries watermarks handwritten documents are a type of pattern evidence this field is commonly involved in civil cases more so than other areas of forensic science.

Current method of DNA typing

STR analysts - these are shorter length polymorphisms know as micro satellites these are repeating sequences 2-7 base pairs long 13 locations were found that contain short tandem repeats gerelectophoresis

History of DNA Typing

STR analysts arose from many years of trial and error.

Polymerase chain reaction

Technique invented by Dr. kary mullis to make exact copies of pieces of DNA it can be used to make millions of copies of any desired strand of DNA in a relatively short time-even with small amounts of material this was nor originally developed for forensic science purposes, but it has become a crucial technique for analysis evidence

red blood cell

They're formed in bone marrow - transpertation of oxygen to cells - no nuclear DNA

additons

a person can alter the writing on a document by adding something later - numbers can be added to a check - even when using colored pen, these can be detected - the chemical characteristics of the ink in the pen may differ, under UV of infrared lights.

Blood information karl landsteiner

a persons blood doesn't contain antibodies that are the same type as the antigens on their red blood cells - this would cause our body to attack itself because it would recognize our own blood as foreign - Karl landsteiner won the nobelium peace prize for his discovery of different types of blood in the ABO system. - before this discovery, people were injured or died due to being given the wrong blood.

expansion of microbial forensics

advances in science have allowed researchers to consider microorganisms for other forensic purposes ''a scientific discipline dedicated to analyze evidence from a bioterrorism act, biocrime, or inadvertent microorganism/toxin release for attribution purposes broadend definition: field that characterized microbial evidence and applies this information to investigations in criminal and civil cases

Properties of the ABO Group

agglutination of red blood cells occurs when two non-compatable types are mixed

Platelets

also known as thronbocytas -blood clotting

what is a question document

any written communication whose source or authentication is in doubt. they do not have to be written on paper ( walls, mirrors, tables_ writing doesn't have to be in ink or pencil ex. blood lipstick -anytime there is commerce between two people involving a document, there is a potential for fraud, forgery, alterations etc - best evidence rule: the rule that governs admissible of documents evidence. only the original document is admitted to court

bsallistics

ballistics is sometimes used interchangeably with firearms examination - these are not necessarily synonymous, but firearm examiners do rely ballisatics - they need to understand characteristics of bullets and pellets as they are fired from a weapon ballistics is the study of projects in motion

size of amunition and barrels

bare diameter the distance from opposing lands - caliber - the bare diameter of a rifled gun barrel - the diameter of the base of cartridge case or bullet gouge: a way of measuring the bore diameter of a shot gun

geometry of blood stain

blood has a fairly high surface tension - blood is very viscous ( flows more slowly than water) - blood tends to adhere to external surface - blood that falls will form a sphere ( not a teardrop as is commonly depicted) - size pf spherical blood droplets depends upon size of surface from which falls ( large surface, more volume, larger droplet) - height of fall changes diameter of blood droplet ( closer to ground smaller diameter) -blood reaches terminal velocity ( highest speed) at approximately 7 feet and diameter will not increase - blood will not break up into smaller droplets if they hit a hard smooth surface water will - blood molecules have cohesive properties that hold the blood molecules together

bullet can case comparison

bullet fired in a barrel then looked under microscope to determine characteristics . - but bullets may not match -rust may cause strations -repeated fireing will cause different striations - some weapon s have inter changable barrels.

ink examinations

can help determine writing instruments or the appropriate age of the document the united states secret service maintains a library of more than 5,000 ink samples that can be compared to a sample from a questioned document -the examiner must not deface the document to obtain an ink sample - there are tools to punch out a hole that is smaller in diameter than the width of pen stroke - popular method: thin layer chromatography - ink examiners can also be used in documentation dating - did the dyes used in the writing ink exist at the same time the document was purposed to have been written?

other types of bio crime

cases of dentist/scientists deliberately infecting patients with infectious diseases such as HIV and heptitis - stains of these bacteria are analyzed and compared to the suspect - in 2012, a laboratory scientist was arrested on federal charges for deliberately infecting patients with HVC - he was HVC positive and contaminated equipment with his blood which were then used on patients. this defendent worked at 18 different hospitals.

loops

comprise 65% of total fingerprints patterns loops have one delta types of loops radial ulnar ulnar loop: opens direction of the thumb radial loop: opens in the direction of the little finger

arches

comprise less than 5% of fingerprints arch patterns do not contain a delta types of arches plain & tented tented arches have ridges that are nearly verticle in slope' plain: arches have more gently sloped ridges.

whorls

comprise of 30% of fingerprints Whorls have two deltas types of whorls Plain: many circular ridges double loop: two overlapping loops that open in opposite directions central pocket loop: loop-print with a small whorl in the middle accidental loop: pattern that does not fit any other or that is made up of two types of other patterns.

confirmatory tests for blood

confirmatory tests are needed because luminol and fluorescein are not specific for blood. - they can give false positives when interacting with certain vegetable extract. - the two most important confirmatory tests for blood 1. teichman test 2. takayama test - these are microcytosol tests -a crystallizing reagent is added to suspected blood - the production of characteristics shaped crystals formed by interactionof the reagent heme is confirmation of blood.

obliterations

crossing out with another writing instrument or writing over words -ex. military document with black lines - can be immersed in methyl alcohol, which can dissolve the marker and make the writing visible - if marker is resistant to solvent then mineral oil and wet the paper and shine a light through it to show writing. some people will try to burn the document - fortunately some inks/pencils burn slowly than paper and writing may be observed.

What is DNA?

deoxyribonucleic acid - it is found in virtually every cell in the body. - red blood cells or nerve cells do not have dna ( do not replicate) - in cells there are two types of DNA 1. nuclear DNA 2. Mitochondrial DNA

Question Document Examiner

document examiners must be familiar with writing, printing, typewritten, inks papers, and methods that are used to alter or obliterate writing. DOCUMENT EXAMINERS - compare unknown documents evidence to know standards or exemplars - they determine the origin or authenticity of documents - restore obliterated or damaged writings document examiners dont spend all their time looking ast documents . they also rely on chemical methods when analyzing ink or restoring writing documents.

non requested examplars

documents written by the subject for porpuse other than the questioned document case - they are colllected instead of requested when suspect is uncooperative, unavailable, incapacitated or deceased - they are already existing documents parts of the suspects everyday life ( business diaries, checks, etc) -these are likely to reflect the subjects the subjects true handwriting because they were not written with the idea that their writing was under investigation. disadvantages -unless the writing identifies the author authenticity, may come into question in court -comparison is more difficult because the non-requested exemplars may not have sufficient number of letters combinations or words

the structure of DNA

double standard helix structure nucleic acid bases along a phosphate backbone - DNA- BASES Adeline-thymine guanine-cytosine - the over all order of the base pairs throughout the DNA ( repeats) and very significant in making protein in the human body -watson and crick 1953 coined the molecular structure of DNA - with help of rosalin frankland x-ray machine in 1952 - she dies four years before they got nobel piece prize.

Fluoresce of fingerprints

fingerprints contain substances that fluoresce certain exposed to certain wave length of light Fluorescence is the emission of electromagnetic radiation (usually light) from an atom that has absorbed energy from another source, causing electrons to shift energy levels in the atom. - strong presence of light may be needed depending on concentration of fingerprint residue - can be used conjectured with cyanoacrylate because prints are nearly indestructible -luqiud fluoresce can be applied to superglue just wash off and laser light is applied.

Dusting for prints

fingerprints powders come in a variety of colors and are commercially available - the types of brushes used should have soft bristles ( camels hair or nylon brush) - the powder color chosen should be contrasts with the surfce being dusted so that the finger print can be visualized better. for plastics magnetic powders are used

Helpful in sexual assult

fleming & harbison 2010 identified bacteria that are specific to vagnial secretion - microbes can be informative of the source of biological evidence, since different parts of our body harbor varying types of bacteria - current methods to identify body fluids are time consuming, non-specific and for some fluids, such as vaginal secretion, there is no methods for identification - in cases of sexual assault, it is sometimes important to determine whether dna OF VAGINAL ORIGIN PRESENT IN SEMAN status - this has important implications for sexual assault cases, since identification of female vaginal secretion in seman stains can corroborate a victims claim.

Analysis workflow

forensic biologist locates saubstance on evidence -> presumptive testing-> determine if human origin -> if sufficent sample is present (qwuantification)- prepare material for DNA testing.

Fraud/Forgery

forgers will obtains authentic samples of handwritting from an author and practice writing in the same style until they are proficient - unless these individuals are experts attempts at forgery can be uncovered - signs of forgery line quality ( thick,smooth) connecting strokes pen lifts starts and stops retouching -forgers will resort to tracing - some forgers bypass these attempts and use their own handwriting = disguised - the person accepting this will usually not be able to tell it is forged . forgery will be discovered after the document has been passed.

Anaylisis of blood

goal: to determine the source - may be multiple locations - may be dry, degreed and putrefied -may be minute amount BLOOD IS PERISHABLE MATERIAL - it will spoil - thrown out of court if bad evidence

first case using DNA

i n the UK in 1980s - first used DNA to convict someone

Disadvantage of examplars

if person knows handwriting is in question they may try to alter it - subject may become nervous and unintended changes in writing - to bypass this these issues the subject may be given breaks and requested exemplars can be taken over several days

splatter blood stains

impact splatter due to blunt force- results of bloodied object receiving a blow - must have blood on surface to create this type of pattern - fist blow does not generally produce impact stain, with exception of gun shot bloodstasin are typically 1-4 mm in size impact stains due to gunshots are smaller in size usually < 1mm, has a misty apperence. cast off splatter- linear pattern of blood leaving weapon such as knife, bat, or hand arterial- large amount of blood under pressure - arc pattern due to breach of major artery ( carotid, femoral) expirated- blood ejected with force from respiratory system -similar pattern to impact spatter, but may contain air bubbles.

vaginal secretion

important when foreign objects has been inserted into vagina - major test for vaginal secretion is to identify glycogenated epithelial cells - cells are formed during menstration and quantity depends on what stage of menstral cycle female is in ( ovulation produces highest concentrations of cells - periodic acid-schiff reagent is used to test for presence of cells - this is not specific test since glycjogenated epithelial cells can be found in other parts of males and females ( although in lower concentration.

history of fingerprints three

in 1883, alphone bertillion produced the first systematic method of personal identification. the system he devised is known as anthropometry or bertiollionage. - this method relies on detailed description of a person, including full length photographs and presence measurements of the body - he created this system on the unproven premise that the human skeleton stops growing . after the age of 18

history of fingerprints: the demise of bertillion

in 1903, will west was commited of a crime and sent to levenworth prison in kansas - when he was being processed at the prison it was discovered there was a man named william west incarcerated as well the two men not only shared the same body measurements but looked the same - the only thing different where their fingerprints - bertiollionage was no longer reliable and was replaced by fingerprints.

things on fingerprints

in dactyloscopy a complete fingerprint consists of the friction ridge skin of the last joint on each finger from cuticle to cuticle - some major ridge characteristics Bifurcation: ridges that split into two ridges looks like y Ending ridge: a simmple straight ridge dot: tiny round dot short ridge: a small, isolated segment of ridge enclosure: a ridge that forks and form a complete circle and then becomes a single ridge circle Trifurcation a ridge that splits into three ridges.

determination of gender

in sexual assult cases it is important to know if the biological smaples belong to a male or female two approaches 1. Analyze locus called amelagenin ( found in a region of xy chromosome) females only have a single peak while males have two peaks 2. analyze the str that are present only the y chromosome ( useful for degrated stains or stains with heavily female mixture.

Ouchterlony Test

in the ouch test, the antigens and antibodies diffuse through the gel toward each other - a precipitate will form where they meet

in the precipitin ring test.

in the precipitin ring test, a ring forms where the antiserum and the blood meet.

Cellular DNA

is organized in chromosomes - 22 matching pairs - 1 pair of sex chromosomes - half from one parent half from other - this is how mental physical and emotional characteristics developed -gene part of chromosome consisting of sequence of base pairs genes make up less than 5% of human dna locus is where a gene is found in the chromosome - have 100,000 genes - variations in chracter is based on variations in the genome -gene that exist in more than one form is polymorphic which are called alleles - some are dominant some are recessive.

history of fingerprints classification system

juan Vucetich an argentine police officer interested in galtons works developed the first classification system. -this system is still used to day in south snd central america but is has been refined - sir Edward henry developed a different classification system that has been modified and is used in the united States and most of Europe

temperature effects on knife handels

knife sterilization 10% bleach solution rinse with 95% ethanol and 3 washes 70% ethonal

Comparison of fingerprints

known fingerprints are collected from subject on a usually used 10 percent - to collect each print each finger is rolled opn printers ink and rolled on from center to outside on the paper card Beginning from 1990 law enforcement agencies began using computer images. prints where rolled into scanning bed which is then uploaded the image in a database - less of damage to prints and the outcome of smudging

types of finger prints

latent fingerprint: a fingerprint not visible to the unaided eye ( usually produced from perspiration/oil on the skin) patent fingerprints a fingerprint that is deposited in paint, blood ( or other material) on a surface and is readily visible plastic fingerprints that is formed in a soft material such as putty.

types of bullets and csracteristics

lead -bullets made of it - increased the velocity bescause bullets to become hotter - this softened the lead inside of the barrell - antimony is now added to harden the lead fully-jacked bullets - these have a layer of copper, brass, or steel that completely, encloses the base of the bullet - this will harden the bullet but reduces its expansion when fired - this in-turn will reduce the detail the bullet picks up from the lands and groves. half-jacket - this jacket is only present on half of the bullet the base while the nose is exposed. cartridges can be made brass, nickei-plated brass or duminum the heads of some cartridges have marking on the surface find a weapons will impart markings on the cartridge ejector/ extractor marks

characters used for comparison of handwriting

like other types of evidence, handwriting has class and individual characteristics as well - class characteristics direction of slant - individual: unusual flourishes at the end of words, ornate capital letters - the document examiners can focus on specific letters or letter combinations and make a chart to show the similarity of the characteristics`` in the known and unknown document

luminol vs. fluorescin

luminal undergoes chemiluminescene when product is formed no additional light is needed because it emits light on its own - florescence undergoes fluorescence , needs outside light source to induce reaction, there are thicker fluorescein reagents that are useful for vertical surfaces - both do not affect DNA typing

Mitochondrial DNA

makes up 1% of DNA energy production multiple copies because alot of mitochondria traces lineage through maternal line more viable than nuclear DNA 37 energy production genes HV1 AND HV2 only two important regions these are the hyper-variable regions can be useful with hair evidence

handwritten analysis

most common and most challenging of examinations handwriting has been admitted into court for over 100 years a persons handwriting contains certain characteristics that are unique and reproducable - no standards for amount of unique features found - has also been questioned in court - little has been reported over individual handwriting - judges have ruled there is no sufficient evidence.

ninhydrin

most popular mehtod excellent in the development of fingerprint on porus surfaces like paper the reagent act with the amino acids in the fingerprint to produce a purple color overlay - ninhydrin sprayed directly on the surface prints may take hours to develop some weak points day to develop hasten the action by heating it to 100 degrees Celsius

crime scene peocessing: rules for firearm

must be photographed with markers or laberls - but dont mark the bullet could destroy evidence - place in small vials or containers - never mark the weapon never stick anything down the barrel - even if you cant get prints of it packaghe it like you would. preliminary examination -before anything find trace evidence - after that find as much evidence as possible

silver nitrate

older method like iodine fuming silver ions react with chlrids ions in sweat residue to produce silver chloride this produces a white insoluble powder

finger print chapter

one of the best know and accepted method of personal identification is matching fingerprints and other friction ridges -friction ridges: raised portions of the outside layer of skin that contains pores and allow skin to have gripping properties -dactyloscopy: the science of comparison of friction ridges structures such as finger prints - finger prints as a method of personal identification has been around for thousands of years - there is still active research on better visualizing methods and how to make the analysis process more objective

CODIS

one of the most important in DNA typing had been the development of local state and national databases it was developed in 1990 and has DNA types from people who have been involved in crimes in order for codis to work all data must be entered as the same type in January 1, 20q67 the fbi needed additional 7 str loci for uploading dna profile codis has three layers 1. local 2. state 3. national

overt vs. covert

overt is bioterrorism aka in package or container covert apparent natural disease.

Postmortems interval

pechai et al 2013 researched the use of microorganisms to determine minimum PMI - researchers determined how microbial succession could help estimate PMI with promising potential, using swine carcasses as a model for human remains goal: detect and identify bacterial community abundance patterns that described discrete time points of the decomposition process

altered blood stains

physiologically altered stains - insecvts interact with the blood and leave trails or transfer stains, blood clots/water/foregin materials mix with the existing blood physically altered stains- void ( absense of blood where it should be) and a wipe existing bloodstain altered by secondary motion through it)

development of typing method

prior to DNA karl landsteiner used blood typing for evidentiary purposes: ABO system ( not as discriminate as DNA typing) DNA fingerprints sir alec jefferies

saliva

produced in the mouth for preliminary digestion of food - no specific test of saliva - alpha-amylase test is generally accepted test for saliva - found in high concentration

Microbial fingerprinting

relatively new area: using skin microbes as trace evidence ( microbial fingerprinting) the basiscs for this technique - individual of skin microbes - temporal stability of skin microbes - my area of research in 2010 fierer found that microbes could be readily recovered from surface like keyboards and these microbes could be attributed to the owner. microbial communities significantly more similar to the owner than to others nishi et al 2014 - analyzed microbial deposits from latent prints and could differentiate 11 out of 12 subjects lex 2015 attributed skin microbials from cell phone to their owners knight 2018 found best surfaces to obtain microbial trace evidence from ceramic and plastic and could recover multiple microbial signatures. using skin microbials for identification is still novel - it is important to consider factors of a crime scene that may affect the viability of using microbial evidence - one potentially important factor and gap in the research environmental temperature my research goal to examine how temperature affects skin microbiomes evidence in forensic created by examininng temperature effects on recovering microbial deposits on knife hanfles

Codis victopry

rita baldo and daughter where murdered in 1992 in Florida where raped found evidence uploaded to codis found it was a convict serving time in Wisconsin. caron sheild was found murdered found evidence under nail matched a notorious rapist oldest cold case solved was linda harmon seman sample was found matched a rapist in mental hospital and arrested him for murder.

requested examplars

samples of handwriting that the author is asked to provide these are taken under conditions established by the document examiner - preferred method of obtaining exemplars, since the examiner has high degree of control over collection process - these types of examplars can be sought by the investigator or ordered by the court -there is no question of authenticity because it was created in the presence of a document examiner. the examplars should always be as similar in all aspects to the unknown unless it is known the questioned document was created in uncomfortable conditions, the subject should be made as conformable as possible the subject should not be show the document in question this is done to make less of a chance they will alter the document - make them right long passages this will make it a sufficient example and gives them more time to slip up or relapse if they forget because of writing for a long time. obtain examplar in context if the questioned document is a check, exemplar should write a check - if in cursive write in cursive - if in pencil write in pencil - if line paper should be lined paper keep things the same as possible`

Luminol

sensitive reagent that oxidizes in the presence of the heme part of hemoglobin - heme is found in RBC's it carries oxygen and carbon dioxide from cells - this reaction results in chemilumeinescence - at a crime scene , the area where the suspect blood evidence is will be darkened. the laminal agent is applied - a bright blue or yellowish-green color indicates the presence of blood. - this color should appear immediately and last at least 30 seconds before another application - luminol has been shown to affect DNA typing

Types of polymorphisms

sequence poly. - different in one or more base pairs with in a gene -ex. the genes are almost exactly alike except for the highlighted part. length poly. Repeating sequence of base pairs called tandem repeats - tandem repeats: repeats that happen right after each other withput any interruption.

comparison of single fingerprint

some states have standards that set fourth the number of points that a fingerprint examiner must find in a known and unknown print in order to declare a match however when there is a exists several standards for the identification this is not truly a standard three levels of friction ridges details level one general features and patterns( arch, whorl, loop not for idividualiztion but can exclude print). level 2. particular ridges. ( bifurcation , islands , dots, etc) compare locations of the ridges in the prints levels 3 these details require a microscope( cuts, scars, ridges contours, pores) these are unique enough to ensure individuality the presence of level 3 depends on the quality of the print.

spines & satellite spatter

spines- protrusions from the parents blood drop Satellites spatter smaller droplets that leave parent drop and land near it -distruption of surface tension snd cohesive properties of blood due to type of target surface

DNA loci for typing

takes advantage of the polymorphic in human DNA modern DNA typing use length polymorphisms frequency of repeats in the human population are estimated DNA database can determine probability of match

what it takes to be a document examiner

tends to acquire a college degree - the path to profession is similar to the fingerprint examiner/firearm analysis - it requires a apprenticeship 2-4 years where the trainee learns from a professional one-on-one. - involves literature reading, research, lectures, exams, problems etc - thee is a voluntary certification through the american board of forensic science document examiners - it is not required but it benefits the document examiner and adds greatly to their qualification especially in court.

history of finger prints

the chinese used finger prints as signatures to sign their legal documents there is no evidence they developed these basic principales to compare fingerprints so it is wondered if this was done to identify the author. - the first organized method of friction ridge identification was done in 1870 when William Herschel, a British official posted in India, started requiring that any contracts involving indigenous people contain imprints of their entire hands. Again there is no evidence that he had developed any systematic way of linking these handprints to a particular person.

history of finger prints 2

the first article discussing fingerprints as an identification method was published in 1880 by henry fauld it appeared in nature - while working as a missionary in japan, he discovered that humans possessed unique patterns in their fingerprints. - he chemically altered his fingerprints but the original patten grew back - fauld suggested dipping fingers in ink and taking these impressions.

how hand writing develops

the methods used in schools to teach hand writing have changed over the years -these methods use a set of printing and writing fonts, and students spend time coping the letters then making words and sentences - you are evaluated by how well you can copy the letters and words - then you develop a penmanship then focus shifts from how writing looks to actually writing - because of this you pay less attention to appearance of writing - this in-turn becomes automatic or second nature -since you no longer pay attention you develop nuances and traits handwriting may be internalized but it is not changed handwriting can change with age these changes are due to diseases, infirmity, advancing age - can be affected by drugs and alcohol - can also change depending on the purpose of writing - for the most part however you keep your unique features

class characteristics in firearm analysis

the number of lands and grooves ( there can be be an even or odd number) - direction of the twist through the barrel - angle of the twist - these characteristics can give the firearms examiner information about the manufacturer and he model. if the proper sized ammunition is used in a rifled ammunition is used in a rifiled weapon, the bullet will expand due to the heat of ignited gunpowder - groves make the land and land makes the grooves on the bullet

iodine fuming

the oldest chemical method - iodine is solid at room temperature and when heated is vapor - reacts with lippids to make a reddish-brown paint - image must be taken quickly because only last a short time - a starch solution should be added to fix the iodine to the print but picture still should be taken -iodine gas is toxic this process should be done in fume hood.

confirmatory test for seman

the only unambiguous test for seminal fluid is the identification of sperm cells - the sperm that will be analyzed in the lab is no longer motile and a stain is used to identify the sperm in the presence of other cellular material the christmas tree stain has developed specifically to visible sperm cells - the pic dye and nuclear fast red are used in the christmas tree stain

minutiae

the ridge characteristics that makeup fingerprints the types and location of these minutiae impact the uniques that forms the basis for fingerprint identification - remember there is no standard for the number of points that must be found

Serology

the study of blood and blood spatter - mistakenly people only think of blood when they think of serology -Pre-DNA testing is still done today if DNA testing is not possible. - not as powerful to individualize a individual. -for case reopening steps 1. analysis 2. identification of other fluids 3. blood stain platter analysis

13 loci for codis database

there are 13 locations on chromosomes that go into the database for a human DNA profile - in 1997 the fbi announced the selection of 13 STR loci to constitute the core of the united states national database, codis all codis STRs are tetrameric repeat sequences

Why is DNA analysis scientifically sound

there are biological explanations for individual specific findings 13 STR loci used to compare DNA samples were selected so that the chance of two differnt people matching on all of them would extremely small. Probabilities of false positives have been explored & quantified lab procedures are well specified and subjected to validation and proficiency testing clear repeatable standards for analysis interpretation and reporting.

white blood cells

these are formed in the lymph node main functions: involve in the immune system contains nuclear DNA

chemical methods for fingerprint visualising

these methods are based on reactions between latent fingerprint residue and certain chemical compounds types of methods -iodine fuming - silver nitrate sugerglue fuming ninhydrin

Deltas

these three patterns are categorized based on the presence or absence of deltas - a delta is a triangular intersection formed by friction ridges curving and changing direction - each of these fingerprints patterns can be subdivided further

DE VS. GRAPHOLOGY

these two often get confused - graphologists claim to be able to discern personality characteristics from someones handwriting. - no scientific backing for this - some judges have accidentally allowed them to testify in court - not allowed to be certified by the forensic document examiner board.

erasures

this involves removing writing from a document through chemical or mechanical means mechanical: rubbing a abrasive across the writting if done correctly there could be no trace of writing. - can tell if erased by the fiber being disheveled in the paper seen through a magnifiing scope chemical - bleaching agent that destroys the dyes in the ink - paper will be discolored in the areas - will be discolored in areas can be seen by uv lights.

superglue fuming

this method was discovered in 1982 by japan scientists experimenting with cyanoacrylate ester to make glue, when heated the glue, the glassware in the hood had visible fingerprints - the prints were whitish and very stable ( rock hard and impossible to remove) Cyanoacrylate reacts with amino acid proteins and fatty acid from finger prints when this process is conducted in slightly humid environment it speeds up the process superglue chambers therefore have water source.

firarm examiners

trace back bulltes and cartridges to a specific weapon - determine whether a weapon can be fired ( deberately disabled or modified weapons, weapons fished out of bodies of water) - determine the distance from which a bullet was fired - serial number restorations - analysis of gunshot residue ( did a person recently fire a weapan) -work with forensic pathologists regarding wound ballistics, or the study of patterns of injury coused by firearms projectilles

Ia the ACE-V method scientific

using scientific method - observation. looking at friction ridges - experiment analysis and comparison of minutiae - evaluation : conclusion ( id, inconclusion, excluded) -verification: someone conducts the same experiment and comes to the same conclusion.

Preliminary Considerations

visual identification not as important as positive blood identification - requires positive identification through scientific means - pro-decals 1. careful preliminary physical examination of the iteam to spot potential evidence 2. careful recording of evidence in its location 3. preliminary screen test that permit a presumption of the presence of certain types of blood

GSR gun shot residue

when a gun is fired not all the gunpowder is bumed completely, and the powder exisits the barrel as smoke and soot. the material that leaves the gun with the bullet is called gunshot residure gunshot examiner looking for three things - antimony -lead - barium

Geometry of blood stains

when blood is thrown or cast onto a surface at an angle, the leading edge of the droplets will be enlarged relative to the back or trailing edge. - the shape of the droplet can be used to determine the direction from which it came as well as the approximate angle relative to the surface it strikes. - angle of impact is determined by measuring length and width of stain, and inverse since of ratio of width to length is equal to angel of impact - be carful to only measure the original shape and stain and not the projections.

Indented Writing

when some one writes hard enough on a pice of the top paper then the impressions could be left on the bottom papers. movies say you can just lightly rub the writing with pencil lead but this does not work and could destroy evidence - what you should do is shine a lamp on the indented writing at an oblique angle and photograph.

Rifling

when someone fires a weapon at a target they would they would like to ensure that the bullet has the best chance to hit where it is aimed - for this to happen the bullet should be made to spin on its long axis as it emerges from the barrels of the weapon - this is accomplished through rifling in the manufacturing process - rifiling: the cutting of curved grooves in a firearm barrel during than during the manufacturing process, this imparts spin on fired bullets which increases stability and accuracy in fights. a rifling broach is used to bore the insults of the barrels from one end the other. this produced land and grooves the grooves are drug in a spinal fashion using the rifiling tool. between each groove, a feature coiled a land will be produced groove: the curved track machined into the barrel of a firearm that causes the bullet to spin upon exit from the barrel land: the part of the gun barrel that is untouched by the machining process that cuts the grooves into the barrell. the rifling broach and its cutting surfaces contain microscopic imperfections that were caused by the tools that manufactured them. - these microscopic imperfections are transferred to the barrel of the gun during the rifiling process. - therefore, the bullet that is fired is not only picking up the lands & grooves but also but also these microscopic imperfections - these appear on the bullet as tiny striations - striations impart individual characteristics - using these marks, a firearm examiner can match a test-fired bullet to one found at a crime scene.