1. forensic science forensic science begins at the crime scene useful information must be...

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“Oh, how simple it would have all been had I been here before they came like a

herd of buffalo and wallowed all over it.”

~ A. Conan Doyle, The Boscombe Valley Mystery, 1892

CRIME SCENE INVESTIGATION

Forensic Science

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Forensic Science Begins at the Crime Scene

Useful information must be carefully, systematically, scientifically, and legally collected. If the crime scene is not treated carefully, it can make vital information not only useless, but even deceptive, pointing an investigation in the wrong direction.

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Crime Scene VocabularyCRIME SCENE: Any physical location in which a crime has occurred or is

suspected of having occurred. Any place where evidence may be located to help explain events.

PRIMARY CRIME SCENE: The original location of a crime or accident.

SECONDARY CRIME SCENE: An alternate location where additional evidence may be found.

SUSPECT: Person thought to be capable of committing a crime

ACCOMPLICE: Person associated with someone suspected of committing a crime

ALIBI: Statement of where a suspect was at the time of a crime.

Copyright © Texas Education Agency 2011. All rights reserved.Images and other multimedia content used with permission.

Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event.

Physical evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession.

Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells.

What will evidence collected at a scene do for the investigation?

• May prove that a crime has been committed• Establish key elements of a crime• Link a suspect with a crime scene or a victim• Establish the identity of a victim or suspect• Corroborate verbal witness testimony • Exonerate the innocent. • Give detectives leads to work with in the case

Types of Evidence

POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime.

The CSI UNIT documents the crime scene in detail and collects any physical evidence.

The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge.

The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death.

SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis.

DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence.

Crime Scene Personnel


Step 1: InterviewThe first step in investigating a crime scene is to interview the first officer at the scene or the victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start.

Step 2: ExamineThe second step in the investigation of a crime scene, which will help identify possible evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene.

Step 3: DocumentThe third step in the protocol involves creating a pictorial record of the scene as well as a rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene.

Step 4: ProcessThis is the last step in the protocol. The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory.

Crime Scene Protocol

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Processing a Crime Scene

Isolate and secure the scene Document the scene Search for evidence Collect and package the evidence

while maintaining the chain of custody

Submit the evidence for analysis


First Officer on the Scene

A – Assess the crime scene and assist the injured

D – Detain the witness(es)

A – Arrest the perpetrator

P – Protect the crime scene

T – Take notes


Secure the Crime Scene

1) Look for signs of life2) Cordon off the scene (only allow

authorized personnel in)3) Bodies should be certified as “dead”

by a medical examiner (ME) before being moved


Survey the Crime Scene

A walkthrough is performed by the crime scene investigator, the first officer, and sometimes the lead detective

Record initial observations of who, what, where, when, and how

Make a plan of action


Observing and Documenting the Scene• Get an overall view to find possible items

of evidence• To identify the points of entry and exit• To consider what may have happened

and mentally outline how the scene should be handled


Document the Crime Scene

Record the crime scene and potential evidence withNotesPhotographySketchesVideography


Notes

Record the following while at the crime scene (details are the key): Date Time Description of the location, weather, and

environmental conditions Description of the crime Location of the evidence relative to other key

points Names of all people involved Any other relevant information


Photography

Nothing should be moved until photographed

Take photos of the scene and the surroundings

Photograph entrances and exits Take wide and close-up photos Use various angles for each piece of

evidence Use a ruler to show size


Videography

Narrate the video Be objective Record from different perspectives


Sketches Draw a rough sketch at the scene

(reconstruct it better later) Include

Date, time, and location Scale Recovered items Important features Accurate distance measurements of

objects (from two fixed points) A legend for description of items A compass designating north Names of investigators, victims, and

suspects


Example: Rough Sketch Include 2 lines to show distance from evidence to a reference point, such as the wall


Search the Crime Scene

When searching a crime scene, wear the following, if available, to minimize contamination Disposable gloves Masks Coveralls with a hood Slippers


Search Patterns

Depend on the size and the location of the crime scene and the number of investigators available

Stick to one pattern and one supervisor Better to collect everything and not

need it than fail to collect something and need it later


Search Patterns (continued)

Spiral – may move inward or outward; best used where there are no physical barriers

Grid – basically a double-line search; effective, but time-consuming

Line (Strip) – best in large, outdoor scenes

Zone (Quadrant) – most effective in houses or buildings; teams are assigned small zones for searching


Search Patterns (continued)

Spiral Grid

Strip or Line Quadrant or Zone


Searching the scene for evidence

•Investigators are looking for anything that shouldn’t be there and anything that might carry trace evidence (such as clothes, documents, rugs, etc.)•Involves extreme care in identifying, packaging, and labeling each piece of evidence.•Special lighting, such as ultraviolet light, may be used to spot body fluids that would be invisible in normal light.


Collect & Package Evidence

Physical evidence must be packaged and collected before time and weather can alter it

Physical evidence – any object that can establish that a crime has been committed or links a crime and the victim or suspect

The Golden Hour – the window of opportunity to collect time-sensitive information or evidence


Collect & Package Evidence (continued)

Each item must be placed in a separate container, and sealed and labeled

The most fragile evidence is collected and packaged first

Different types of evidence require specific or special collection and packaging techniques

The body is the property of the coroner or medical examiner; collection of evidence on the body is done by that department



Containers such as vials, envelopes, plastic bags, paper bags, canisters, and cardboard boxes are good packaging devices

Most items should be placed in a primary container and then in a secondary container

Trace evidence may be placed on a piece of paper which is then folded in a “druggist fold” and placed in a secondary container



Containers should be sealed with tamper proof tape, and dated and initialed

Each package should contain Description of contents Date, time, and location Agency and collector’s name Case number Victim’s name(s)

Never package two items from two different sources or locations


Chain of Custody There must be a written record of all

people who have had possession of an item of evidence, beginning at the time of collection

Every person who handled or examined the evidence must be accounted for

Chain of Custody should include Date and time of transfer Location of transfer To/From names Purpose of the transfer


Cases where crime scene was compromised:

• Manson murders• O. J. Simpson case•The Enrique Camarena case• JonBenet Ramsey case•Jeffrey MacDonald case

Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana

Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass.

Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials.

Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva.

Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons.

Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires.

Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects.

Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock.

Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin.

Investigating the Evidence Forensic Science disciplines at the Illinois State Police Crime Labs


National Databases

Crime Scene Investigators can submit evidence for analysis to several national databases based on the type of evidence

Examples include Automated Fingerprint Identification

System (AFIS) Integrated Automated Fingerprint Identification

System (IAFIS) Combined DNA Index System (CODIS) Integrated Ballistics Identification System (IBIS) International Forensic Automotive Paint Data

Query (PDQ)


Resources

0135158494, Saferstein, Richard. Forensic Science: An Introduction. New Jersey: Pearson Prentice Hall, 2008.

0757518257, Ball-Deslich, Barbara and John Funkhouser. Forensic Science for High School. 2nd Edition. Kenall/Hunt, 2009.


What evidence would you collect?


OJ Simpson case

Upon arriving at 12:13 AM, investigators spotted a small large pool of blood that led up to a female body, later identified as Nicole Simpson, about fifteen feet away from the sidewalk. Her back was aligned with the stairs behind her, and the left side of her face was pressed against the walkway. She was fully dressed in a black dress, and her neck was cut from one ear to the other, nearly severing her head in the process. Blood emanating from the wounds drenched her entire body.


OJ Simpson case

Shortly after this discovery, investigators discovered a male body, identified as Ronald Goldman, slightly to Simpson’s right, behind a bush. The fully clothed body lay sprawled out on his right side, and blood covered his entire body. He had multiple stab wounds over his body. His eyes were open. In between Goldman and Simpson lay a beeper, a knit cap, a set of keys, a bloody left-hand glove and a bloody white envelope. Bloody footprints and blood drops led away from the bodies to the back of the property.


Investigating the Scene

After securing the scene with 18 officers, the police force began to survey the area and take pictures of the general surroundings.

Investigators went to contact O.J. Simpson, Nicole Simpson’s ex-husband, at his house 2 miles away to ask him to collect his children. There, they immediately noticed blood on the driver’s door of Simpson’s Bronco. Fearing that Simpson had also become victim to murder because no one answering the phone, investigators climbed over the stone wall and unlocked the door to the property.

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They came across a blood-stained right-handed glove on the walkway that looked similar to the bloody left-handed glove found at the crime scene, and blood drops near and in two cars, a Saab and a Bentley. Further investigation of the Bronco nearby presented a multitude of blood stains around and inside the car. Blood lead from the car to the front door of the house. Soon a photographer was brought on scene to take pictures, and shortly after the blood spots and glove were confiscated without a warrant under the belief that the evidence was in plain view.


OJ Simpson Evidence Errors "There were two identical containers

sitting side by side, one marked 'bile' and one marked 'urine,' and the wrong stuff got put in the wrong bottle. The defense people know all about this because they had a representative in the office. We caught it in plenty of time."


OJ Simpson Evidence Errors A deputy coroner conceded that

Mrs. Simpson's stomach contents had been discarded and that the knife wounds could have been more carefully examined. He also acknowledged that medical examiners had waited an unusually long time -- 10 hours -- to examine the bodies.