The Crime SceneThe Crime Scene

Chapter 2Chapter 2

Processing The Crime Scene

Forensic Science begins at the crime scene

- Physical Evidence: Any object (natural or manufactured) that can establish that a crime has been committed or can provide a link between a crime and its victim or between a crime and its perpetrator.

Fundamental Practices at a Crime Scene

• Secure and Isolate Crime Scene• Record Crime Scene• Photograph Crime Scene• Sketch Crime Scene• Maintain excellent Notes• Conduct Systematic Search for Evidence• Collect and Package Physical Evidence• Maintain Chain of Custody• Obtain Standard/Reference Samples• Submit Evidence to Library• Maintain Safety at Crime Scene

Secure and Isolate Crime Scene• Responsibility of the first officer arriving on the

scene.• Medical assistance must be given to anyone in

need• Scene must be preserved and protected

because every person entering scene is a potential destroyer of evidence (intentionally or accidentally)– No unauthorized personnel (including spectators,

unauthorized police officers and media) on scene– Ropes, tape, barricades used to secure scene– Record maintained of all people entering and leaving

crime scene

Record Crime Scene

Once the crime scene is secure, the lead investigator evaluates the area. There is a very limited amount of time to process scene before it gets disrupted by various personnel– Boundaries of crime scene determined– Initial walk-through conducted – Strategy developed to process scene– Photograph and/or sketch scene– Take detailed notes

Photograph Crime Scene

• Photographs must be taken without altering the scene or moving objects (unless there are injured people that need medical attention).

• If anything gets moved, photos may not be admissible in court as evidence.

• Detailed notes should be taken to override this issue.

Photography cont’d.

• Crime scene must be photographed thoroughly (from various angles)

• All adjacent areas as well• All points of entry and exit• If scene includes body, pictures of the position and

location relative to entire scene must be taken• Close-ups of injuries, weapons• Once body is removed, the surface under body must be

photographed• Each piece of physical evidence must be photographed

in its original location next to a ruler or other measuring device AND a number I.D. card

• Video recorders are also being used these days, but have not replaced still photographs

Sketch Crime SceneSketch Crime Scene

Once photographs are taken, the crime-scene Once photographs are taken, the crime-scene investigator will sketch the scene (a rough investigator will sketch the scene (a rough sketch, since there is no time to make a polished sketch, since there is no time to make a polished one)one)

A rough sketch employs geometric shapes and A rough sketch employs geometric shapes and letters and numbers.letters and numbers.

A finished sketch is created with mush more care A finished sketch is created with mush more care and detail. Computer aided drafting (CAD) can and detail. Computer aided drafting (CAD) can be employed to do this.be employed to do this.

Rough Sketch

Finished Sketch – Hand Drawn

Finished Sketch (CAD)

Maintain Excellent Notes

• Must be a constant activity

• Must include a written description of scene and location of all objects of physical evidence

• Tape-recorded notes can be more advantageous – faster. But at some point in time the tapes must be transcribed into written/typed notes.

Conduct Systematic Search for Evidence

• Physical evidence may be large or microscopic, therefore searches have to be conducted with extreme care and have to be thorough.

• Hap-hazard searches will lead to important clues being missed or lost.

• Systematic searches, using specific patterns are used.• Critical areas of the scene may be vacuumed with

portable vacuum cleaners equipped with special filters• The search for physical evidence must extend beyond

the crime scene to the autopsy room of the victim – the medical examiner will contribute to the evidence list with results of toxicology and pathology examinations of various body parts, organs, tissues, etc.

Spiral Search

Grid and Zone

Also called the Quadrant Method

Parallel

Vacuum sweeper attachments

The following list of physical evidence is collected to be sent to

the forensic laboratory:• Victim’s clothing• Fingernail scrapings• Head and pubic hairs• Blood (For DNA typing)• Vaginal, anal, oral swabs (sex-crimes)• Bullets recovered from body• Hand swabs from shooting victims (GSR

tests)

Collect and Package Physical Evidence

• Physical evidence must be collected and packaged correctly so it does not change from the time it was collected to the time it is processed by the crime lab. Changes such as evaporation, contamination, breakage, etc.

• Each different piece of physical evidence must be packaged separately.

• Evidence must be handled with forceps (gloved hands only) or similar tools

Collect and Package Physical Evidence

• Plastic pill bottles, manila envelopes, glass bottles: for storing hair, fibers, glass and various small or “trace” evidence.

• Paper with “druggist fold”: an alternative way to store trace evidence.

Blood-stained materials must be stored in paper bags or manila envelopes

Blood-soaked clothing must NOT be stored in air-tight containers because the trapped moisture may cause the growth of mildew and mold and destroy the blood.

All clothing in fact, must be air-dried and individually stored in paper bags.

Charred clothing or debris on the contrary, MUST be stored in air-tight containers so that evaporation of volatile petroleum residues does not occur.

Maintain Chain of Custody

• A list must be maintained of all persons who came into possession of a particular item of evidence.

• Failure to do this may will lead to serious questions regarding the authenticity and integrity of the evidence and it may not be admissible in court.

• Each time an evidence container is opened and closed, it must be sealed with a label with the examiner’s name, date and location of the item.

• If the evidence is moved to another location/lab, the date of this transfer must also appear on the label.

• In addition, a complete record of all persons in touch with the evidence is maintained and these persons may be summoned to court to testify during court proceedings.

Obtain Standard/Reference Samples

• All evidence must be compared to with a known (standard/reference) sample

• For example, blood-stained evidence must be accompanied by blood or buccal samples from both the victim as well as the suspect(s)

• Same is true with hair, fibers, soil, etc.

Submit Evidence to Library• Can be delivered to lab by personal delivery or

mail delivery but certain materials cannot be mailed – explosive, certain chemicals, live ammunition, etc.

• Receiving lab must get a case history or any such report along with the evidence.

• There should be a clear request of type of examination for each piece of evidence – however, an analyst may perform other tests on the pieces of evidence if necessary (in addition to the tests requested)

• An evidence submission form must be completed with a list of all evidence items being submitted for tests.

Crime-scene Safety

• All CSI have to be extremely careful due to the increasing spread of HIV, Hepatitis B&C, and other diseases carried in bodily fluids.

• Inoculations against Hepatitis B are made available to all law enforcement officials according to OSHA (Occupational Safety and Health Administration)

CSI Safety Guidelines:• Double layer of latex gloves• Protective Tyvek® shoe covers• Tyvek ® or Kleengard ® coveralls or suits (liquid repellant)• Particle mask/respirator, goggles/face shield to prevent exposure to dust,

mist, body fluids, etc.• Be aware of sharp objects like broken glass, knives, needles, etc.• Use biohazard labels when collecting materials hazardous to health.• All gloves, masks, suits must be disposed of in red biohazard bags, taped

shut and sent to a proper facility for incineration.• Note-taking should be done with fresh, uncontaminated gloves to prevent

contamination of pens, pencils and notepads.• Torn or soiled protective gear must be removed immediately and replaced

with a fresh one, AFTER the individual disinfects the contaminated body area with 10% bleach solution, antimicrobial wipes, etc.

• Absolutely no eating, drinking, smoking in the crime scene or laboratory.• All non-disposable items such as cloth lab coats, etc. must be placed in

yellow bags labeled “Infectious linen” and sent to a proper facility for laundering and disinfection.

CSI Clean-up crew

Legal Considerations at a Crime Scene

• The removal of any person or evidence from a crime scene must be done in conformity with Forth Amendment privileges:– The right of the people to be secure in their persons,

houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Warrant or no warrant

Therefore, search warrants are required. A warrantless search can only be conducted under the following circumstances:

1. Existence of an emergency2. To prevent immediate loss or destruction of

evidence3. Search of a person or property of the person

during his arrest4. Search an seizure with the consent of the

persons involved

THE END