The Crime Scene Chapter Two Forensic Science

Physical Evidence Any object that can establish a crime has been committed or can link a crime and its victim and its perpetrator You must be able to recognize and properly preserve physical evidence at a crime scene

The Crime Scene Step 1: Secure and isolate the crime scene to prevent contamination, destruction of evidence Step 2: Record the scene – take lots of notes Step 3: Photograph or video the scene - before it is disturbed – close-up and distance shots (p46) Step 4: Sketch the crime scene - rough sketch first; then finished sketch incorporating the notes (p 47-8)

Value of Physical Evidence Physical evidence is used to Show that a suspect where they had no right to be. Establish a suspect's presence at the crime scene. Establish probable cause (motive) for the event. Establish proof beyond a reasonable doubt of YOUR version of the event.

Value of Physical Evidence Human factor of physical evidence: Physical evidence "can't lie, quit, die, forget, or get fired” Testimonial evidence may change or source may become "nonexistent' between original and court version Physical properties of physical evidence: Cannot change But the identification or interpretation of the evidence can change or be incorrect

"Golden Rule" of Crime Scene Management "Never touch, change, or alter anything until it has been documented, identified, measured, and photographed... when a body or article has been moved, it can never be restored to its original position.” Exceptions to the Golden Rule: (1)If a weapon could be used to cause harm/death to someone at the scene. (2)If the potential exists for an item/evidence to be lost, contaminated or destroyed (weather, traffic, etc) Transient evidence is that type of short-lived evidence subject to damage or destruction by exposure to the elements. Evidence which changes with the passage of time.

Crime Scene Search FIRST OFFICER on the scene MUST Secure and protect the scene. ･ To "secure" is to close access ･ To "protect" is to deny access. Identify, remove, and separate the witnesses from the scene. Other actions may include: Perform preliminary survey of the scene. Establish control of the scene Determine extent of search

Crime Scene Management Crime Scene Investigators Develop preliminary theory. Identify physical evidence. Begin documentation. Record narrative of the scene. Notes - keep forever. Audiotape - use new tape, maintain tape in chain of custody as evidence, transcribe. Videotape (sight/sound) - "hears all, sees all," disconnect sound.

Photographic record of the scene. Record the scene with photographs and video if available, Photograph the scene in progressive sequence Overview (entire scene) ending with close-up of each item. First without measurement scale, then with.

Finished sketch

SKETCHING THE CRIME SCENE Draw a Rough Sketch of the scene. Document the relationship physical evidence items, including locations and distances from FIXED OBJECTS. Experience helps to develop ability to identify the most useful items at the scene.

CRIME SCENE SEARCH General Rules: Detailed search of scene, leave "No stone unturned” Record, collect, mark, and preserve evidence. Be aware that collecting one type of evidence may destroy another type. Choose the appropriate search pattern. Perform final survey of the scene and double- check documentation and thoroughness of search.

Inward Spiral Search Pattern The inward spiral search: The CSI starts at the perimeter of the scene and works toward the center. Spiral patterns are a good method to use when there is only one CSI at the scene.

Outward Spiral Search The outward spiral search: The CSI starts at the center of scene (or at the body) and works outward.

Parallel Search The parallel search: All of the members of the CSI team form a line. They walk in a straight line, at the same speed, from one end of crime scene to the other.

Grid Search Pattern The grid search: A grid search is simply two parallel searches, offset by 90 degrees, performed one after the other.

Zone Search Pattern The zone search: In a zone search, the CSI in charge divides the crime scene into sectors, and each team member takes one sector. Team members may then switch sectors and search again to ensure complete coverage.

Are the doors and windows locked or unlocked? Open or shut? Are there signs of forced entry, such as tool marks or broken locks Is the house in good order? If not, does it look like there was a struggle or was the victim just messy? Is there mail lying around? Has it been opened? Is the kitchen in good order? Is there any partially eaten food? Is the table set? If so, for how many people? Are there signs of a party, such as empty glasses or bottles or full ashtrays?r full ashtrays If there are full ashtrays, what brands of cigarettes present? Are there any lipstick or teeth marks on the butts? Is there anything that seems out of place? A glass with lipstick marks in a man's apartment, or the toilet seat up in a woman's apartment? Is there a couch blocking a doorway? Is there trash in the trash cans? Is there anything out of the ordinary in the trash? Is the trash in the right chronological order according to dates on mail and other papers? If not, someone might have been looking for something in the victim's trash. Do the clocks show the right time? Are the bathroom towels wet? Are the bathroom towels missing? Are there any signs of a cleanup? If the crime is a shooting, how many shots were fired? The CSI will try to locate the gun, each bullet, each shell casing and each bullet hole. If the crime is a stabbing, is a knife obviously missing from victim's kitchen? If so, the crime may not have been premeditated. Are there any shoe prints on tile, wood or linoleum floors or in the area immediately outside the building? Are there any tire marks in the driveway or in the area around the building? Is there any blood splatter on floors, walls or ceilings?lls or ceilings

Procedures for Evidence Collection Physical evidence must be collected INDIVIDUALLY Packaging is VERY important: Ashes – clean paint can Bloodstained items (dry)- paper bag Bloodstain items (wet)- paper bag Dirt – manila envelope MUST label each item Items MUST be sealed Chain of Custody

Evidence Collection Item should be kept in as original condition as possible Evidence should be submitted as intact as possible Each item collected should be bagged separately Bloodstains and other biological evidence should be collected in paper bags, manilla envelopes or druggist folds to prevent the growth of mold. Stained clothing should be air dried before wrapping Charred debris from a fire must be placed in airtight containers

Chain of Custody All evidence MUST be sealed at the time of collection All evidence has a complete list of anyone who comes in contact with the item

Medical Examiner/Forensic Pathologist Answers basic questions: Who was the victim? What injuries are present? When did the injuries occur? Why and how were the injures produced? Performs autopsy to establish cause of death Estimates TOD (time of death)

Post Mortem Terms Rigor mortis - muscles relax then stiffen occurs between hours (“stiff”) Livor mortis - blood pools closest to the ground when the heart stops beating leaving Algor mortis - body temperature drops at a rate of 1-1/2 degrees F per hour until it reaches ambient temperature

Forensic Anthropologist Identification and examination of human skeletal remains Bones can reveal sex, approximate age, race,and skeletal injury Create facial reconstructions Ex: Case Study (pages 60-1)

Forensic Entomologist Examines insects and their relation to criminal investigation Blowflies, bottle flies, house flies, lay eggs, which hatch into maggots, then grow into adult flies Ex: The number of eggs, maggots &adult flies can determine the approximate TOD and length of decomposition time.

EDMUND LOCARD France’s “Father of Forensics” in Lyon, France. Dr. Locard was a medical examiner during WWI. Believed that every contact produced an exchange of physical material. Locard’s Exchange Principal Any action of an individual, and obviously the violent action constituting a crime, cannot occur without leaving a trace.”