Crime Scene Investigation

Taylor, PVMHS2015

Locard’s Principle of Exchange

0When a person comes in contact with an object or another person, a cross-transfer of physical evidence occurs.

0These transferred materials, constitute trace evidence.0Study of the material can determine the intensity, nature

and duration of the transfer.0 Example: more transfer occurs in a fist-fight than would in a

simple brush of the arm.

Trace Evidence: transferred material

0Pet hair0Fibers0Fingerprints0Human hair0Sand and soil0Paint chips0Broken glass0Feathers 0Drop of blood0Building material

http://www.fbi.gov/about-us/lab/scientific-analysis/trace

Types of Evidence

Direct0Evidence that proves an

alleged fact such as an eyewitness account, a video or dash cam, a confession.

Circumstantial0Evidence used to imply a fact

but not prove it directly.0Can be either physical or

biological in nature.0Trace evidence is a type of

circumstantial evidence.

Circumstantial evidence classified

Physical evidence0Synthetic fibers0Weapons0Bullets0Shell casings0Fingerprints0Footprints0Shoe prints0Tire impressions0Tool marks

Biological evidence0Body fluids

0 Blood0 Semen0 Saliva0 Etc.

0Hair0Skin cells0Fingernails 0Plants 0Pollen0 Insects

Class vs Individual Evidence0Class evidence: Material that

connects an individual or thing to a certain group.

0Blood type0Hair0Soil0Tire marks0Anything that can be

narrowed to a group but not a specific individual.

0 Individual evidence: Material that identifies a specific individual or thing.

0Fingerprints0DNA0Anything that can be matched

specifically to an individual.0 Footprints0 Shoe prints with specific wear

patterns0 Tire marks with specific wear

patterns

Collecting and storing evidence0 Liquids and arson remains: airtight, unbreakable containers0 Biological evidence: breathable containers

0 Wet evidence should never be placed in a plastic container while wet, DNA will degenerate and evidence may grow mold.

0 Glass or ballistic evidence: carefully wrapped and placed in an envelope to prevent scratching or breakage.

0 Drugs or pharmaceuticals: sealed paper container, original pill bottle, or heat-sealed bags.

0 Documents: cellophane or plastic envelope.0 Lifted latent prints: sealed envelope0 Articles containing suspected latent prints: fastened to wood or

cardboard for transport, handled as little as possible.0 For more information visit

http://nvlpubs.nist.gov/nistpubs/ir/2013/NIST.IR.7928.pdf

The Crime Scene Teamwho is at the scene of the crime?

0Police officers: Generally the first to arrive at a crime scene. 0Crime-scene investigators: Photographers, sketch artists,

recorders to record data, & evidence collectors.0Medical examiner: Necessary if the crime scene includes a

dead body.0Detectives: Interview witnesses & crime-scene investigators

about the evidence.0Forensic “specialist's”: Entomologists, anthropologists,

psychologists.

The 7 S’s of CSI…

1. Secure the scene2. Separate the witnesses3. Scan the scene4. See the scene5. Sketch the scene6. Search for evidence7. Secure the evidence

Secure the scene0Securing the scene is the responsibility of the first responder.

0 Check the safety of all individuals 0 Restrict unauthorized entry to preserve evidence0 Keep a security log0 Separate witnesses

Separate witnesses0Witnesses should not talk to each other (as you know!)

0 They could compare accounts0 Key witnesses could create a “story”

0 Investigator questions to witnesses include:0 When did the crime occur?0 Who called in the crime?0 Who is the victim?0 Can the perpetrator be identified?0 What did you see happen?0 Where were you (positioned) when you observed the crime?

Scan the scene0The crime scene needs to be scanned to determine where

photos should be taken.

0Scan the scene to determine whether it is a primary crime scene (location where crime took place) or secondary crime scene (a location other than the initial crime scene that holds evidence that relates to the crime)

See the scene

0Photos need to be taken:0 in-situ distant

0 triangulation of stationary objects should be included as reference points

0 in-situ close up0with & without a ruler if possible

0 in collection paper with evidence label filled out and visible.

Sketch the scene0An accurate sketch of the crime scene (to scale) is necessary.

0 The position of any evidence/persons should be indicated.0 All objects should be measured from two immovable objects.0 North should be labeled.0 A scale of distance should be included.0 Landmarks or large/stationary objects should be included:

0Furniture0Trees0Hedges0Fences0Cars0Doors0Windows 0Street0Staircase

Search for evidence0 Investigators may use a spiral, grid, linear, or quadrant

pattern should be used depending on the number of investigators and the nature of the crime scene.

0This allows for a systematic search, ensuring that no one area is left unsearched.

0Alternate light sources may be required to locate some evidence (such as hair and fibers).

0A special vacuum cleaner is sometimes used to collect evidence.

0Flashlights, forceps, and magnifying glasses may also be used to collect small pieces of evidence.

Search patterns

Secure the evidence0Evidence needs to be properly packaged, sealed, and labeled.0Every piece of evidence needs an evidence label cataloging:

0 Case number0 Item inventory number0 Description of evidence 0 Name of suspect0 Name of victim0 Date and time of recovery0 Signature of person recovering the evidence0 Signature of witness present (if any) during evidence collection

0Every piece of evidence must also have a chain of custody label on it.

What’s a bindle?0 After evidence is allowed to air dry, it is packaged in a paper bindle.0 The bindle then in placed inside a plastic or paper container.0 The outer container is sealed and a chain of custody document and an

evidence label are attached.0 The size of the bindle depends on the size of the evidence. 0 Wrapping:

0 Choose appropriate size paper0 Crease paper as shown below0 Place evidence in X position0 Fold left and right sides in 0 Fold in top and bottom0 Insert top flap into bottom flap, then tape closed

Chain of custody0 Maintaining chain of custody is essential.0 Every time a piece of evidence is opened and resealed, the chain of

custody log needs to be signed.0 This process ensures that all persons who have handled the evidence

are accounted for and that the evidence is responsibly handled from crime scene to courtroom.

0 If just one “link” in the chain is broken the evidence may become inadmissible.

Biohazard0A biological agent that is a hazard to

the health of humans or the environment.0 Medical waste0 Biological toxins0 Microorganisms

0Most frequently used in CSI to indicate the presence of blood and body fluids of unknown origin.

0Sharps containers are for needles any other sharp medical instrument (IV, cath, scalpel, etc.)

Analyzing the evidence0Evidence will be sent to the forensic lab.

0 Danvers crime lab – Criminalistics0 Maynard – DNA analysis0 http://www.mass.gov/eopss/law-enforce-and-cj/criminal-inve

stig/crime-lab/lab-locations-and-directions.html

0Lab technicians are specialized to process specific types of evidence 0 DNA0 Arson & explosives0 Firearms

0Lab results are sent to the lead detective0Evidence is interpreted and compared to witness’

statements.

Reconstructing the scene0Based on the lab results from evidence analysis, detectives

will form a hypothesis of the sequence of events that occurred from before the crime was committed through its completion.

0 Investigators must determine how all evidence fits:0 Was evidence planted or staged?0 What are all the possible scenarios that could have occurred?0 How does the evidence (or how do the scenarios) compare to

witness accounts?0 Investigators must keep an open mind (no filters) as they piece

the puzzle together.

Staged crime scenes0When evidence does not match the testimony of the

witness.0Common crimes that are staged:

0 Arson0 Suicide/murder0 Burglary

0As an investigator you:0 Treat all deaths initially as a homicide.0 Corroborate statements with evidence facts.0 Reconstruct the event.0 Conduct all forensic examinations to establish the facts.

Case study review

0Review the case study from the book and the accompanying article.

0Using your knowledge on investigating crime scenes, explain how evidence collected at the crime scene was critical to your case.

Case study review #1: Lillian Oetting

Three Chicago socialites were murdered in Starved Rock State Park, Illinois. All three women had fractured skulls. Their bodies, bound with twine, were found in a cave. Near the bodies of the women, a bloodied tree limb was found and considered to be the murder weapon. Because all three womenhad been staying at a nearby lodge, the staff of the lodge was questioned. Chester Weger, a 21-year-old dishwasher at the lodge, was asked about a blood stain on his coat. He said it was animal blood. He agreed to take a lie detector test and passed it. He was re-questioned and took a second lie detector test and passed it as well. The blood was examined by the state crime lab and found to be animal blood as Weger had indicated at questioning. The case reached a dead end.

Investigators decided to revisit the evidence. The rope used to bind the women was examined more carefully. It was found to be 20-stranded twine sold only at Starved Rock State Park. Identical twine was found in an area accessible to Weger. He again became a prime suspect. The blood on his coat was reexamined by the FBI Crime Lab and found to be human and compatible with the blood of one of the victims. Weger submitted to another lie detector test and failed it. Weger was found guilty for the murder of one of the women, Lillian Oetting, and has spent more than 45 years in prison. He recently petitioned the Governor of Illinois for clemency, saying he was beaten and tortured into making the confession. He still maintains his innocence.

Case study review #2: The Atlanta child murders

Wayne Williams is thought to be one of the worst serial killers of adolescents in U.S. history. His victims were killed and thrown into the Chattahoochee River in Georgia. Williams was questioned, because he was seen near where a body had washed ashore. Two kinds of fiber were found on the victims. The first kind was an unusual yellow-green nylon fiber used in floor carpeting. Through the efforts of the FBI and DuPont Chemical Company, the carpet manufacturer was identified. The carpet had been sold in only 10 states, one of them being Alabama, where Williams lived. Thus, the fibers found on the victims were linked to carpet fibers found in Williams’ home.

Another victim’s body yielded the second type of fiber. This fiber was determined to be from carpeting found in pre-1973 Chevrolets. It was determined that only 680 vehicles registered in Alabama had a matching carpet. Williams owned a 1970 Chevrolet station wagon with matching carpet. The probability of both types of fibers being owned by the same person was calculated. The odds against another person owning both carpet types were about 29 million to one. Williams was convicted and sentenced to two life terms.