Forensic Science Final Exam
schedule 1 drugs
no accepted medical use, high potential for abuse. Lack of safety for use. Marijuana, LSD, Heroin, Morphine, Mescaline, Peyote, GHB, Cocaine, etc.
Blood Alcohol Concentration (BAC)
percent weight per volume, blood system or breath. Current legal measure= 0.08% breath= blood concentration= alcohol in brain Volume of alcohol in blood is 2100 times than what is being exhaled out
Gas Chromatography (GC) (drugs)
(packed column and capillary column) components with a greater affinity for moving gas phase will travel through column quicker than those with affinity for stationary liquid phase
A-B-O Blood typing system
+/- Rh factor Individualize people (narrow it down)
Alcohol and the Law
.08 alcohol level is a violation of the law. Commercial drivers- 0.04 % 5th amendment guarantees all citizens protection against self incrimination "implied consent" law- operation of a motor vehicle under alcohol must consent to a BAC test or lose their license. Schmerber v California- application of the Fourth Amendment's protection against warrantless searches and the Fifth Amendment right against self-incrimination for searches that intrude into the human body Missouri v McNeely- obtain a search warrent prior to the drawing of a person's blood for alcohol testing
The Analytical Scheme (toxicology)
1. remove and isolate toxic agents from biological material (acidic vs basic) 2. identify drugs present (screening and confirmation) - screening: TLC, GC, immunoassay -confirmation: "fingerprint", confirm its the drug, ensure conclusions. GC/MS, blood tests, urine tests.
Restriction Fragment Length Polymorphisms (RFLPs)
15-30 bases in lengths and repeats itself up to a thousand times. Cut out by restriction enzyme, fragments are separated and sorted out by electrophoresis *PCR has replaced RFLPs *biggest impact of RFLP was monica lewinsky and bill clinton case
DNA
1985 Alec Jeffreys- named process of isolating DNA as DNA fingerprinting
alcohol distribution
2/3 of body volume. Fat, bones and hair contain little alcohol, liver contains most. In decedents (dead) the brain, cerebrospinal fluid, or vitreous human can be used to determine alcohol levels
Alcohol in human body
3 steps of metabolism Absorption Distribution Elimination -all alcohol enters blood stream when its been absorbed, a maximum alcohol level is reached in the blood Factors that affect rate of alcohol: Total time, alcohol %, amount of alcohol, presence of food (quantity, type), body size, medication Avg human drinking absorption on empty stomach: 30-90 minutes Full stomach: 2-4 hours
Blood types
A- Antigen A, Antibody B (42 % of pop.) B- Antigen B, Antibody A (12 % of pop.) AB- Antigen B, no antibody, universal receiver (3% of pop.) O- No antigen, Both antibody A and B, universal donor (43% of pop.) Determining blood type by adding Rh factor also determines antibodies
ABO genes code for...
ABO is a coding gene. "A" allele= transferase A , adds Nacetylgalactosamine to antigen "B" transferase= differs from "A" by few amino acids, transfers galactose "O" gene= codes for defective transferase (frameshift mutation)
elemental analysis
Absorption of spectroscopy (UV, IR, Visible) Emission Spectroscopy- emit unique light based on ID of substance and light absorbed. Collects and measures various light energies given off by atom
Human Genome Project
An international collaborative effort to map and sequence the DNA of the entire human genome.
Heredity
Antigens are genetically controlled traits, inherited from parents, ID traits to compare people Fertilization, Allele, Heterozygous, Homozygous, Genes
antigens and antibodies
Antigens- stimulates body to produce antibodies against it (immune response), located on surface of red blood cells, usually proteins and carbohydrates Type A- A Antigens Type B- B antigens Type AB- A + B antigens Type O= No A or B antigens -Rh factor or D antigen is present= positive (+) Not present= negative (-) Antibodies- y shaped proteins found in plasma/serum, tags antigen and binds to it. Antibody is named for antigen in which it is specific for.
Questioned documents
Any object that contains handwritten or typewritten markings whose source or authenticity are not known, but which is still relevant to the outcome of a legal proceeding. Document examiners= years of training and practice, sufficient collection of exemplars is crucial to identify a source No two individuals write exactly alike, can be resemblance all handwriting has a general style. Zaner-Bloser handwriting and Palmer handwriting
Scene of a fire
Area of origin, accelerant containers, marks, v shaped patterns Collect evidence in paint cans, cuts off oxygen supply, designed to trap volatiles; vapor is removed with a syringe (head space) Analysis- gas chromatography Vapor concentration technique- charcoal strip in airtight container, absorbs much of the vapors during heating
Spectrophotometry (drugs)
Beer's Law. measures quantity of radiation that a particular substance has of absorption of a chemical (UV or IR) regions. IR is more complex, produces a "fingerprint", good for comparison
Handwriting
Children tend to have similar handwriting, stand letter forms, conscious not subconscious Unconscious handwriting of two individuals can never be identical Variations: angularity, slope, speed, pen pressure, letter and word spacing, relative dimensions of letters, connections between letters, pen movements, writing skill, finger dexterity, spelling, punctuation, phraseology, grammar Specific number of characteristics between known and unknown document. Judgement call made by the expert examiner in the context of the case Challenges: not enough comparison points, written out to disguise actual handwriting. Sober vs drunk, influence of drugs or alcohol Exemplars: recreate situation, writing implement, paper type, words, and combinations of letters Normal variations- no one signs the same way every time (signature)
Mixtures (explosive)
Chlorate mixture- give up oxygen more efficiently than nitrates (fireworks) Gas air mixtures- form of low explosive, natural gas escapes into a confined area and mixes with a sufficient amount of air
Confirmatory Test for semen
Christmas Tree Stain" - microscopic test Dyes the heads of the sperm red Dyes the tails of the sperm green Sperm HY-Liter= fluorescent stain for sperm heads, fluorescent tagged antibody PSA (prostate specific antigen)- protein present in seminal plasma, inject into rabbit, produces polyclonal antibodies, use antibodies to test for human stains of semen
Screening tests (drugs)
Color tests Marquis Test- heroin and amphetamines. Heroin, morphine and most opium derivatives turn purple. Amphetamines, and meth turn orange-brown Dillie-Koppany- Barbiturates turn violet blue Duquenois-Levine- marijuana, solution A-2% vanillin, and 1% acetaldehyde, solution N- conc. HCl. Solution C- chloroform, turns purple Van Urk- LSD 1% pda, 10% conc. HCl and ethyl alcohol, turns blue purple Scott Test- cocaine. Solution A- 2% cobalt thiocyanate in 1:1 water:glycerine. Solution B- conc. HCl. Solution B- chloroform, turns blue, than clear pink then blue
Preliminary Analysis (drugs)
Color tests can be used for preliminary not confirmatory Microcrystalline test- studying size and shape of crystals formed when drug os mixed with specific reagents.
Competitive vs Noncompetitive immunoassays
Competitive: enzyme multiplied immunoassay techniques (EMIT), detecting drugs in urine, antibodies will bind to drug in urine. Competition between analyte in sample and added labelled analyte, bind to antibody. EMIT most useful for THC metabolite Noncompetitive: ELISA, analyte in sample is bound to an antibody site on a surface, captures it. Amount of labelled antibody on site is measured= concentration of analyte. Analyte in sample binds to labelled antibodies
Karl Landsteiner
Discovered that blood can be grouped into different types, A, B, AB and O.
Stimulants
Drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, and Ecstasy) that excite neural activity and speed up body functions.
club drugs
Drugs that first gained popularity at dance clubs and raves. MDMA, GHB (Sexual assault) , Rohypnol (roofies-sexual assault), Ketamine, Methaphetamine.
Make up of an explosion
Gas build up most explosives confinement is necessary container shell should be tight enough to confine gases outward expansion of gases= blast effect, artificial wind Speed- Low explosives deflagrate (burn)- firearms, very rapid oxidation that produces heat, light and a subsonic pressure wave High explosives detonate- creation of a supersonic wave within the explosive charge Smokeless powder- slow burn, releases more gas Black powder- fast burn, more smoke Gun cotton- more powerful explosive Gun powder- less powerful explosive
CODIS (Combined DNA Index System)
National database of DNA data obtained from individuals convicted of sexual assaults or homicides
Mitochondrial DNA
Outside of Nucleus inherited from mother mtDNA reference sample can be obtained from any maternally related relative
Nature of blood
Plasma- fluid portion of blood, composed of water, 55% of blood content Solid materials suspended in plasma- 45% of blood content. RBC's (erythrocytes), WBC's (leukocytes), platelets
Forensics of Blood
Preliminary color test: benzidine test, kastle meyer test, luminol, blue star, hemastix Benzidine and KM tests are based on observation of hemoglobin in blood possesses peroxide like activity Phenolphthalein- laxative, acid- base indicator Blood Crystalline tests- add specific chemicals to blood, expect characteristic crystals (Takayama, Teichman) Blood Confirmatory Test- RSID detects presence of human glycopherin A Blood Origin Test- precipitin test= human or animal bloodstain. Gel diffusion= another version of precipitin test
high explosive
Primary explosive: ultra sensitive to heat, shock or friction detonate violently instead of burning primers extreme sensitivity, rarely used in homemade bombs Secondary Explosive: insensitive to heat, shock, or friction normally burn rather then detonate if ignited in open air dynamite, tnt, petn, rdx commercial and military blasting explosives extremely rapid, supersonic shock wave Dynamite- different strengths Ammonium nitrate based explosions- water gels, emulsion, ANFO, fertilizer -rdx is most popular and powerful of military explosives, encountered in form of C-4 (rdx and tnt) -PETN= cordlike explosives containing a core of high explosive material TATP- homemade explosive that has been used by terrorist organizations, friction and impact sensitive, mix nail polish remover and hydrogen peroxide, why only small amounts of liquids are allowed on planes High explosives need to be detonated by an initiating explosive, flame is not enough (blasting caps, mercury switches)
Locating non visible stains (or testing for semen)
Semen will fluoresce. Acid phosphatase test- acid phosphatase is up to 400x more in seminal fluid than in any other bodily fluid (includes false positives) Oligospermia- abnormally low sperm count Aspermia- no sperm at all
Collection of soil evidence
Standard references: 100 foot radius of crime scene, various intervals, 10+ samples Only top layer (situation: body in ground) Packaged separately in glass vials Soil and alibi locations for comparison Soil must not be removed from shoe or garment, wrapped with paper individually. Not air tight Collect lumps when vehicle is found, compare layers to loose soil from scene to see if one layer matches
Semen
Tests 1. Presumptive possibility that a body fluid present narrow down possibilities 2. Confirmatory identify bodily fluid definitively
Collection and packaging of DNA evidence
Touch DNA- transferring DNA via skin cells through touching an object Low copy number- quantity of DNA below normal level of detection, courts sometimes do not allow this to be admissable (amanda knox case) Sources of DNA: blood, semen, saliva, skin cells, sweat, hair, and bone Documentation: photograph, sketch, notes, analysis of bloodstain pattern by expert Evidence: Minimize contact, every item packaged separately, victim and suspect do not enter crime scene after fact, no plastic or airtight containers only paper and breathable containers, red bio hazard label must be attached, blood and soil in clean glass or plastic container.
Vented vs unvented fire
Vented more soot unlimited supply of oxygen Unvented less soot smoke combustion ends because oxygen decreases
Narcotics (opiates)
a class of opium-related drugs that suppress the sensation of pain by binding to and stimulating the nervous system's natural receptor sites for endorphins
schedule 111 drugs
accepted medical use. Lower potential for abuse than schedule 1 or 11, moderate or lower physical or psychological dependence
schedule 11 drugs
accepted medical use. Severe physical or psychological dependence
Document
age (2-3 years) increase age difference, standard becomes less representative, basic writing changes in most adults are comparatively slow Minimize conscious efforts 1. sit comfortably at a desk or table without distraction 2. dictated words should be same as contents of questioned documents 3. dictated text should occur at least 3 times 4. Signature exemplars, document examiners should be consulted several pages of writing (20 pages)
Sex determination by STR
amelogenin gene is included in str kits because provides sex of dna contributer gene for teeth pulp shorted by 6 bases in x chromosome then in y chromosome type STRs located on the y chromosome (male) called y-strs, prove useful when multiple males are involved
Nuclear Forensics
analyze nuclear materials recovered, isotopes of elements Neutron activation- measures gamma ray frequencies, identifies elements, requires access to a nuclear reactor
capillary electrophoresis
automated STR fragments move through column under influence of electrical potential at a speed that is related to length
Alcohol elimination
body begins to eliminate it, eliminated through oxidations or excretion (breath, urine sweat) Elimination varies on enzyme productivity, varies as much as 30% in individuals (0.015% per hour)
Alcohol testing
brain tissue is best way but blood is more legal. Breath test at 34 degrees celsius ratio of alcohol in the blood to alcohol and breath is 2100:1 collect and measure alcohol content of alveolar breath, alcohol is unchanged in breath Field testing- sobriety tests like walking straight in a line used to estimate a motorists degree of physical impairment
Erasures, Obliterations, and Alterations
changed so original content may be hidden Erasures- scratch or abrade writing to remove (eraser, knife, etc) infrared/ uv imager, indentations Chemical- strong oxidizing agents that interact with dye and erase Alterations- changing written documents by adding new characters -illuminate doc with blue/green light, IR sensitive film, luminescent properties of inks Obliterations- overwriting or crossing out to hide original writing, can be revealed by infrared radiation if inks used are different Changing sequence of document- someone changed or added something new to it Charred document- IR photography can reveal contents, reflect light off of papers surface Indented writings- partially visible depressions on paper underneath the one on which visible writing was done, apply electrostatic charge to visualize indented writing Digital imaging- editing program can be used to make adjustments such as lighting, darkening, color and contrast controls
Type of Substance in body
clues: victims symptoms, post mortem, pathological examination, examination of the person's personal effects, nearby drug containers or chemicals
Arson
complex and difficult circumstances to investigate Modus operandi- offenders pattern of operation - accelerant on clothes= used to start fire -relevant chemical materials. ID trace amounts of chemicals chemically fire is a type of oxidation (exothermic- releases heat)
Fire spreads through heat transfer
convection- movement of fluid conduction- hear or electric current (direct contact) radiation- rays or waves of particles Flashover- combustible fuels simultaneously ignite, explosion like Accelerant- gasoline, kerosene, etc, kick start a fire
Inductively Coupled Plasma (ICP)
creates changed particles that emit light of characteristic wavelengths corresponding to the identity of the elements present
Immunoassay
detecting drugs of abuse in blood and urine, antibodies that react with drugs do not exist naturally Antigen-Antibody reaction- put antigen into a body to produce different antibodies, designed to particular site on the antigen of interest (polyclonal antibodies) Monoclonal antibodies- identify one specific type of polyclonal antibody to produce one antibody over and over again
Mass Spectrometry (MS) (drugs)
direct connection between GC and MS, allows each component to flow into MS as it emerges from GC fragmentation of compounds by high energy electrons in the MS will produce a distinct pattern of substance being examined
Explosives
distilled water, baking soda, acetone, hydrochloric acid. Individuals trained in: bomb disposal, bomb site investigation, forensic analysis, criminal investigation Explosion= very fast combustion, creates pressure waves, requires oxidizing agents, chemicals that supply oxygen Black powder is made up of: potassium nitrate, charcoal, sulfur AS heat is applied, O is released and reacts with C and S to produce heat and gases Nitroglycerine (not stable)- dynamite main component, (C,O,N,H), oxygen recombines to produce large values of CO, H2O and nitrogen gas
Collection of blood for testing
drawn under medically accepted conditions by a professional. add anticoagulant and a preservative before sealing, stored in fridge until delivery
Depressants
drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions
trace elements
earths crust, elemental impurities, present in concentration of less then 1%. Provide visible markers for points of comparison
Sexual Assault
finding evidence of semen on a rape victim indicates some kind of sexual intercourse has taken place. Protect evidence. Physical evidence collected: pubic combings, external genital swabs, body area swabs, head hairs, blood sample, buccal swab, fingernail scraping, urine specimen, all clothes
Collection of Substances in body
fluid samples (urine) fluid in tissues Deceased: med examiner decides what biological specimens to send to toxicology lab Living: fewer options, urine taken, sample of blood
Testing Blood for Alcohol Content
gas chromatography, compare resulting alcohol peak areas to known standards to calculate BAC auto analyzers measure conversion of alcohol to acetaldehyde, serum alcohol is converted to a blood alcohol dividing by factor 1.16
Fire
gas phase chemical reaction that emits heat and light; combustion gases are phases of matter that can burn Pyrolysis= breaks down solids into fuel gases Three elements: oxygen, heat, fuel (wood, etc) Fire development: fuel limited, decay (collects most evidence) Fire behavior (ventilation limited) -heat is transferred to gases, thermal plume moves upward, heat gas layer forms, pressure increases, combustion continues, oxygen in room depletes, combustion stops. Death caused by asphyxiation (With Ventilation) -impact of outside air on fire growth, hot gases flow out, cool gases flow in ( steady source of oxygen) -char levels Area of origin: vshaped pattern formed by thermal plume
non drug poisons
heavy metals and carbon monoxide Screening: Reinsch test Confirmation: X ray diffraction
Paint
hit and run cases, burglary Mixture of components: Solvents, Pigments, Additives, Resins/Binder (give most info- chem analysis) Car Paint: Electrocoat primer, Primer Surfacer, base coat (inorganic) Pyrolysis gas chromatography- decompose polymer chains and analyze fragments Infrared spectroscopy Emission Spectroscopy, ICP, and X Ray spectroscopy can analyze inorganic elements in paints
Forensic Serology
identification of blood and other body fluids (semen, vaginal fluid, saliva)
Forensic Toxicology
identifying presence of drugs and poisons in: body fluids tissues organs
Detecting drugs in hair
measuring long term abuse of drug. drugs present in blood defuse through capillary in blood through to the hair
short tandem repeats (STRs)
most successful DNA profiling procedure, STR's are locations on the chromosomes that are 3-7 bases in length (repeating) STR blue kit (triplexing) Product rule Mini STRs- portion around STR region , looking at damaged DNA (hair or burned bodies)
ICP
mutilated bullets and glass fragments gold, silver, antimony, copper, etc compare elemental profiles of unknown and known samples
Type script
photocopier, fax, printing devices; 10 samples for side by side comparison make and model of the printing device Photocopiers- gradual change, shift or duplication of irregularly shaped and distinctive pattens may aid in examiner dating documents Fax machines- patterns from debris and other materials, microscopic examination of transmitting terminal identifier (TTI) Printers- impact= strike the page non impact= do not strike page (inkjet and laser) Printing tech- paper, ink etc -toner examination, model of machine, side by side comparison (questioned v exemplar), emissions spectrum (metals) Typewriters- vertical and horizontal alignment , hard or soft element hits paper (unabomber)
Tandem Repeats
portions of the DNA molecule contain sequences of bases that are repeated numerous times, fillers or spacer between coding regions of DNA (distinguished by how ACTGs repeat)
Hallucinogens
psychedelic drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input
Blood
red blood cells, white blood cells, platelets, plasma. Enzymes, proteins (hemoglobin), inorganic substance.
Collection of Paint Evidence
remove all layers of paint, use blade to cut out 1/4 inch square, collect with care to keep intact. Use tweezers or paper to collect paint chips. Collect tool (used for break in), collect reference paint samples
TLC (drugs)
separate components of a mixture. mobile liquid phase ultraviolet light
Confirmatory Determination (drugs)
specific test to identify a drug substance to the exclusion of all other known chemical substances. Qualitative- relates to identity of material Quantitative- determination of percent comp. of the components of a mixture Chromatography-separating and identifying the components of a mixture, analyzing drugs Henry's Law- fixed ratio of concentration between volatile compound in air and its concentration in liquid, ratio remains constant for a given temperature
Gilbert v. California
supreme court upheld the taking of handwriting exemplars before the appointment of counsel outside of protection of 5th and 4th amendment rights, does not violate search and seizure
polymerase chain reaction (PCR)
technique that uses the natural process that occurs in our body in a test tube. Replicating small quantities of DNA or broken pieces of DNA at a crime scene 1. Dna is heated to separate it 2. Second primers are added 3. Dna polymerase and free nucleotides (ATGC) are added- first cycle completed 4. Cycle is repeated 25-30 times
Ignition
temperature needed to get over barrier, pretty high flash points are room temperature and below (gas in cars)= if appropriate input is given, just enough to get into vapor state physical state of fuel ---> pyrolizes combustion low form= smoldering (gas forms thin line around outside of solid not enough energy to burn inside) Spontaneous combustion- rare, heat increases and is not ventilated, medium to catch fire will eventually reach its ignition point (hay bales)
red blood cells (erythrocytes)
transport oxygen from lungs to body tissue
Forensic Examination of Soil
value of soil= transferability between scene and criminal Geological maps Comparison Side by side visual comparison (soil chart) Elemental analysis (ICP, R-transmissions) Dry vs Wet Density, texture or size of soil particles Mineral Content Microscope:Minerals and rocks- color,shape, density, and refractive index Polarizing light microscope (birefringence) Minerals, rocks, matter, artificial debris building materials, safe insulation cannot individualize to specific location
Chemical analysis of ink and paper
visible light micro spectrophotometer (uv, vis, IR) compare reflectance Thin layer chromatography- ink comparisons, punch out ink sample, soak in solvent, separation of components US secret service and IRS maintain the US International Ink Library (tag their inks in manufacture process) Paper Examination: general appearance, color, weight, watermarks, fiber identification, characterization of additives, fillers and pigments, UV light comparison
Fire Lab
when fire started/how/cause how fire behaves in an open/closed space analyze debris and damage
Toxicology of Alcohol
widely abused, ethyl alcohol, 40% of traffic deaths. Blood alcohol concentration = Brain alcohol concentration
Collection and analysis after explosion
wire mesh screens used to life through debris paint cans, airtight containers, no plastic, keep things isolated crater=origin=loose soil charred areas and detonators porous surfaces-residue seeps in Pipe bombs- pipe cap, pipe threads debris- locate black powder and smokeless powder, acetone used to dissolve Screening: Ion mobility spectrometer- time it takes to move through drift region is characteristic; radioisotopes color spot tests thin layer chromatography GC-MS