pcc 274 exam 1
Ligature
An assailant has placed a ligature around the victim's neck and tightened it for purposes of controlling, silencing and/or killing the victim
physical evidence
anything used, left, removed, altered or contaminated during the commission of crime by either victim or suspect
forensic science
application of sciences to law &spectrum of sciences is enormous
latent fingerprint
latent-is when you cant see something use methods to enhnce such as powder, inhydrate, patent print, alternate light source
Classifying Impact Spatter
low, medium, high velocity spatter -Low Velocity Spatter: Drops with diameters of 4 mm or more normally produced by an applied force of up to 5 ft/sec. -Medium Velocity Spatter: Drops with diameters from 1-4 mm with an applied force of 5 to 25 ft/sec. -High Velocity Spatter: Drops with diameters of less than 1 mm from an applied force of 100 ft/sec or faster.
textile materals
may deform impact, may cause drop to break up and increase satellite drop, may act as drum lead launching satellite drop into air
Transfer
wet object with blood contacting a non-bloody surface and transferring blood to that surface
Edmond Locard (1877-1966)
whenever 2 objects come into contact with one another there is exchange of material between them
Hans Gross (1847-1915)
wrote the first treatise describing the application of scientific disciplines to the field of criminal investigation -judge and public prosecutor
documentation and photography
Purpose: permanently record the condition of the crime scene and its physical evidence -time consuming
Mathieu Orfila (1787-1853)
*father of forensic toxicology *1814- treatise on detection of poisons & their effects on animals
brief history
-16th century Europe in gathering of information on the cause & manner of death- heavy dependence on eye witnesses -18 century started collecting evidence to solve crimes-looking to science
first responding officers
-Assist the victim and prevent any changes to the victim. -Search for and arrest the suspect if that person is still on scene. -Detain any witnesses; do not take them back to the scene if at all possible. -Protect and secure the crime scene. -Document all movements, alterations, or changes made to the crime scene and pass this information to crime scene investigators
Properties of Human Blood
-Biological Properties: --To tissues - Oxygen, electrolytes, nourishment, hormones, vitamins, antibodies --From tissues - Waste products -Plasma → Red and White blood cells and platelets --Clotted plasma = serum Nuclei of WBC = DNA
DNA database
-CODIS (combined DNA index system) - Maintained by FBI -All 50 states have agreed to establish data banks of DNA profiles of convicted sex offenders and other crimes dependent on state laws
csi objectives
-Defining the Crime Scene -Uses Information from Physical Evidence in Criminal Investigations -General Crime Scene Procedure -Crime Scene Documentation and Forensic Photography -Collection and Preservation of Physical evidence -Crime Scene Reconstruction
video recording
-Document the recording by use of a placard. -Begin with the scene surroundings. -General orientation of the scene. -Victim's viewpoint. -Camera techniques. -Original video
evidence form
-Evidence seal MUST ALWAYS be initialed and dated -every piece of evidence must be listed on evidence form -each piece of evidence is exchanged between officers and examiners the "Chain of Custody" must be signed. -taking possession of evidence- date and initial on package
sketching
-Final task -Units of measure/Correct perspective -Types of sketches: Rough,Final/Finished -Perspectives: Overhead/Bird's eye view,Elevation/Side-view
BloodStain Analysis
-First studies in 1895 by Eduard Piotrowski (University of Vienna) used patterns in blood created via interaction of blood surface, fluid mechanisms determined bloodstains.
forensic science focus areas
-Forensic Anthropology - Forensic Chemistry - Forensic Biology - Forensic Entomology - Multimedia Forensics
2 types of physical evidence
-Individual Characteristics: A piece of evidence that is unique and can be identified to the exclusion of all others. (Fingerprints &tool marks, bulletes, DNA) ``more individual=higher probability fro match -Class Characteristics- Features shared by all members of a group or class (Footprints)
blood pattern analysis
-It is the "what" of bloodshed and can help reconstruct a scene --Direction of travel of the blood droplets --Distance of blood source to target surface --Angel of impact of the blood droplet --Determination of blood trails --Nature of the object used to cause the bloodshed --Interpretation of contact or transfer patterns
Uses and Information from Physical Evidence
-Linkage of persons, scenes, or objects -Provide investigative leads -Information on the corpus delicti or modus operandi -Proving or disproving witness statements -suspet identification -identification of unknown substances -reconstruction of a crime
defining the time scene
-Location According to Criminal Activity (Primary vs. Secondary) -Size (Macro vs. Micro) -Type (Homicide, Robbery, etc.) -Condition (Organized vs. Disorganized) -Physical Location (Indoors, Outdoors, Vehicle, etc) -AssociatedCriminalBehavior (Passive vs. Active0
NIBIN & IBIS (National Integrated Ballistics Information Network & Integrated Ballistic Identification System)
-Maintained by BATF -Allows firearms examiners to compare markings on bullets and shell casings recovered from crime scenes
crime scene survey (walk through)
-Mental beginning for a reconstruction theory. -Note any transient (temporary) or conditional (the result of an action) evidence present and requires immediate protection or processing.
fibers
-Natural and synthetic fibers that are transferred between victim and suspect are useful in establishing a link between the two. -An Alternate Light Source (ALS) is helpful in locating fibers.
Collection and Preservation
-Primary and secondary containers -Sealed: Completely cover openin, Initialed, timed and dated -Labeled:Collector and date/time/location -paper best packaging -wet evidence: wait to dry then seal in plastic for no mold -small dry samples like paint, hair, fibers- use any clean paper fold it after and label it
photography
-Purpose: Provide a true and accurate pictorial record. -Types of photos: Overall, Mid-range, Close-up -Close-up photos especially if they maybe used in a comparison should be photographed with and without scale -camera:high resolution digital camera
explosives
-Residue from the explosion and unexploded bomb that are linked together from the same powder can traced back to the powder manufacturer. -ATF= agency responsible for the xplosives see from debris
firearms and ammunition
-Size of bullet identifies the caliber of the firearm -Lands and grooves on bullet identify the type of firearm -Parts found at scene identify the size of the firearm (need to find bullet barrel)
satellite spatter
-Smaller droplets of blood that have detached from the main blood volume at the moment of impact -factos: volume, freshness, surface, & distance
comparison of a specimen analysis
-Subject specimen (unknown) and a standard specimen (known) are compared through tests and examination to determine weather they have a common origin. -ex: shoe size & pattern -With more and more mass produced items the uniqueness of a fiber or a piece of physical evidence is diminished.
surface texture
-Surface texture and the stain's shape, size, and location must be considered when determining a bloodstain's direction, dropping distance, and angle of impact. -harder and less porous the surface, the less spatter results.
forensic scientist & CSI
-The work of the forensic scientist has little value if the evidence has not been identified, recorded, collected, and preserved at the scene of the crime. -responsibility of the forensic scientist to train and educate law enforcement in the identification, recording, collection, and preservation of the physical evidence.
physical properties of blood pattern/spatter
-To create spatter surface tension must be overcome by an external force -Shape of drop in air is dependent upon the molecular forces acting upon its surface
AFIS (automatic fingerprint identification system)/ IAFIS (integrated"'_
-a statewide database of scanned and encoded fingerprint information to search known files for comparison and matching to unknown fingerprints -.Latent fingerprint points are marked and submitted for search -maintained by F.B.I.
Directionality and Angle of Impact
-determined by measuring the degree of circular distortion. -At right angles= circular; as the angle decreases, the stain becomes long. -The direction of travel of blood striking an object may be discerned because the pointed end of a bloodstain always faces the direction of travel. -The lower the angle of impact to the surface, the longer the bloodstain pattern.
void patterns
-an object blocks the deposition of blood spatter onto a target surface or object and the spatter is deposited onto the object or person instead. -The blank space on the surface or object may give a clue as to the size and shape of the missing object or person
forensic scientist
-applies their scientific knowledge to analyzing of evidence courtroom testimony is a huge part of forensic scientists duties -persuade jury to accept their conclusions or result of analysis
body fluid
-blood, semen, urine, and saliva -alternate light source (ALS) useful in locating evidence -can be analyzed and origins determined
arterial spatter
-caused by an injury to the heart, or a main artery, and the pressure of the continuing pumping. -site of the initial injury to the artery can be found where the pattern begins with the biggest spurt. The trail away from this point shows the victim's movement.
5 elements of an investigative report
-completeness -conciseness -clearness -correctness -courteous and fair (unbiased reporting)
Francis Galton (1822-1911)
-conducted first definitive study of fingerprints and their classification -1892- treatise entitled fingerprints
Castoff patterns
-created when a blood-covered object flings blood in an arc onto a nearby surface. - produced by a bloody fist, or weapon, between delivering blows. -Appear linear in distribution
identification of a substance
-determine the physical or chemical identity with as near absolute certainty as existing analytical techniques will permit. -first requires the adoption of testing procedures that give characteristic results for specific standard materials. ----depending how much sample evidence you have like alot of cocaine the more you can test if you have a little cant do much -2nd, requires that the number and type of tests needed to identify a substance be sufficient to exclude all other substances.
Leon Lattes (1887-1954)
-developed a procedure to determine blood type for dried bloodstains
purpose of recognizing physical evidence
-examination of physical evidence by a forensic scientist is usually undertaken for identification or comparison purposes. -enhance the collection and analysis of material remains -the jury to determine how important a piece of evidence is -important to communicate effective findings -Sometimes the identification and analysis can suggest a probable relationship ex: there is a circle immersion on victim= something was putting pressure on victim
Alexander Gettler (1883-1968)
-first forensic chemist to be employed in NYC
expirated bloodstain pattern
-forcefully expelled blood from the nose or mouth that has accumulated in the lungs, sinuses, and airway passages of the victim as a result of trauma (similar to beatings and gunshots) -Vacuoles - ruptured air bubbles -Dilution from saliva or nasal secretions -blood will be with extra material
documents and handwriting
-handwriting can be identified back to person -grammar if person keeps spelling wrong -inks and papers can be traced to manufacture -obliteration and burned documents can be retrieved
hair
-human or nonhuman -DNA from root, drug analysis on hair by cutting a mm of strand
area of origin
-impact bloodstain pattern is the area in a three- dimensional space from which the blood was projected. -show the position of the victim or suspect in space when the stain-producing event took place.
Daubert v. Merrell Dow Pharmaceuticals, Inc. Guidlines
-judge ensures experts testimony is reliable/ relevant - Has the scientific technique been tested -Has it been subject to peer review and publication -The technique's potential rate of error -Standards controlling the technique's operation -Has the method attracted widespread acceptance within a relevant scientific community
flow pattern
-made by drops or large amounts of blood flowing by the pull of gravity. -show movements of objects or bodies while the flow was still in progress or after the blood dried.
Impact spatter
-occurs when an object impacts a source of blood -mist-like dispersion -factors: available blood, caliber, location -# of blows inflicted have effects on resulting pattern
Autopsy process
-removal of organs -inframammary incision -examination of brain -organs weighed and dissected -underlying bruising -police custody
Frye v. United States
-set the guideline that to be admissible the evidence must have been processed using a procedure or techniques that is "generally accepted" by scientific community in the field it belongs. - new techniques=reviewed by other scientists
Class Characteristics
-something everybody has -class characteristics are useful but have limitations help elimate people or hypothesis -better to try to get it unique (ex: plastics bags: can look up from what store it came from or receipts
crime scene reconstruction
-sort out the events surrounding the occurrence of a crime. -The method used to support a likely sequence of events is observation and evaluation of physical evidence, and statements made by those involved with the incident,
crime lab units
-standard: physical science, biology, firearms, documents,photgraphy -optional: toxicology, fingerprints, polygraph, voice print
drug evidence
-the package= the label and the writing is the same from multiple cases -the pills have a certain marking/ label shows purity of drug -uniform bags
scientific method of investigation
1) Who committed the crime? - investigator formulates a hypothesis 2) What? testing of the hypothesis through scientific experimentation 3)When? the hypothesis is validated by experimentation and becomes scientific evidence admissible in court
Wipe
Created when an object moves through exiting blood and alters the original stains appearance
4 major federal crime labs
FBI, DEA, ATF, US Postal Inspection Services
Albert Osborn (1858-1946)
Father of Document Examination
Rigor Mortis
Full rigor is present 8-12 hours after death, under normal temperature and conditions
notes
Guidelines: Notification information, Arrival information, Scene description, Victim description, Crime scene team
Impact mechanics
If the substrate is rigid, textile and other substrates behave similarly, if deflects some energy may be absorbed. if rough spreading surface can induce drop break up
drop volume
Increased surface area of the source object = a larger volume with larger drops
Forensic Pathology
Studies decease, it causes, and its diagnosis. Specialized areas- anatomic and clinical
expert testimony
a factor in determining a person's guilt or innocence. So the forensic scientist may be required to testify about their methods, results and conclusions at the trial
Blood smear
a non descript transfer stain on a surface from a bloody object that has no recognizable features
Swipe
a wet bloody moving object contacting a non-bloody surface that may indicate direction. typical of hair or fabrics
Fluid Mechanics
airborne-blood launches into air, can often be identified from non-absorbent surfaces Air resistance- gravity acts on drop. drops travel in a straight-ish line, sometimes slows it down air flow my deflect drop Lands on surface- my spread, break up, retract, and even depart fro surface. if surface is absorbent blood may wick into material
Back Spatter
also known as blow-back spatter, is projected backward from the source. - if the bullet does not exit the body, a gunshot produces only back spatter.
BPA
based on sound scientific principles, Assume what is observed after bloodletting events is same as when it occurred unless altered . valid on non-absorbent surfaces and textiles. for small drops it is rarely valid on textiles.
Should documentation be done before or after evidence collection?
before
Forensic Anthropology
concerned primarily with the identification and examination of human skeletal remains. bones can determine sex,age, race, and injury
Alphonse Bertillon (1853-1914)
devised first scientific system of personal identification, using body measurements known as anthropometry in 1879
Drag
exiting pool is altered by movement of a victim or object
Thermal Trauma
exposure to excessive heat or cold
testimonial evidence
form of a statement under oath in response to questioning
asphyxia
interruption of oxygen of the brain
Coroner duties
investigate body, scene with law enforcement, determine: Cause, Manner, Mechanism of death, order autopsies, collect property of the deceased.
Mechanism of death
is a biochemical or physiologic abnormality produced by the cause of death that is incompatible with life
Forward spatter
is projected outward and away from the source.
Causes of death
is the disease or injury that initiated the lethal chain of events
N.A.S.H
natural, accidental, suicidal, homicidal
Can items of evidence be packaged together?
no -one evidence collector
Pools
only occurs when blood collects in a level and undisturbed places. if the blood is on an absorbent surface may be absorbed throughout the surface and diffuse creating a bigger pattern.
Electrical Trauma
passage of electricity through a person
area of convergence
point on a two-dimensional plane from which the drops in an impact pattern originated.
Small Bloodstains on Textiles What Can They Tell Us?
provide a good repository for blood for future analysis,Comparison of stain characteristics with textile condition may indicate inconsistencies of Lying on hard or soft surface Repellent or wicking, and can tell a lot about texture
Chemical Trauma
rugs of abuse Barbiturates, diazepams, and opiates Produce coma followed by cessation of breathing and death Exceptions - Marijuana and cocaine.At high doses - death from seizures, extremely high body temperatures, and uncontrolled quivering of the heart
powder residue
the farther you go away= less powder, dust, residue -3in, 6in, 12, contact
Manner of death
the fashion in which the cause of death came to be, undetermined, NASH
The Investigation of Death
to determine its cause and manner, a pathologist must be prepared to present physical evidence to support his/her conclusions about the cause and manner of death.
Calvin Goddard (1891-1955)
used a comparison microscope to determine if a bullet was fired from s specific gun -published study of tool marks on bullets