Crime Scene Processing Forensic Science: Crime Scene Processing

Duties of Field Team & Crime Lab Field Investigative Unit Crime Lab Scientist Secure the crime scene Receive/sign for evidence Photograph the crime scene Review paperwork Search the crime scene Complete chemical and/or physical tests on evidence Properly collect and package evidence Complete an analysis of the findings Complete proper forms: Evidence Submission & Chain of Custody Provide expert testimony Deliver or ship evidence to proper processing site

Ordinary vs. Expert Testimony Ordinary testimony is restricted to statements concerning what the witness actually saw or heard. An ordinary witness is prohibited from stating opinions about the case and from quoting statements made by other people. Expert testimony is that given by a specialist who has been recognized by the court as having expert knowledge about evidence in the case. An expert witness is allowed to express an opinion about the validity of the evidence in a case and may quote the statements of other experts in support of an opinion.

Secure & Isolate the Crime Scene Responsibility of first officer on scene Get help for injured Preserve & protect area by roping off Clear all except essential and authorized persons from crime scene area

Separating the Witnesses Witnesses must not be allowed to talk to each other. The following questions need to be asked of each witness: When did the crime occur? Who called in the crime? Who is the victim? Can the perpetrator be identified? What did you see happen? Where were you when you observed the crime?

Record the Scene Required for trial Common methods: Photography – always display a scale, from many angles Sketches – Rough & Finished Notes - Ongoing throughout the process Photographs & a rough sketch must be completed before any evidence is collected or searched for.

Sketches: Must include: Outline of room Location of doors, windows, & furniture if inside trees, vehicles, hedges & other structures if outside Positions of all recovered items of physical evidence. All objects should be measured from two immovable landmarks. Name of illustrator, date, compass rose, scale, & legend for physical evidence

Sketch, cont.

Sketches, cont.

Types of Crime Scenes There may be more to a crime scene than first meets the eye. In fact, more than one crime scene may exist, depending upon how the crime was committed — not to mention where. Crime scenes therefore are considered either primary or secondary. The primary crime scene is where a crime actually occurred. A secondary crime scene is in some way related to the crime but is not where the actual crime took place. In a bank robbery, for example, the bank is the primary scene, but the get-away car and the thief's hideout are secondary scenes. In the case of a killer who commits a murder in someone's home but transports the victim's body to a river for disposal, the victim's home is the primary scene, and the killer's vehicle and the point along the river where the body was dumped are secondary scenes.

Search the Scene All areas including entry & exit points Method choice depends on type of crime & size/location of crime scene

Method Size/Location Type of Crime Quadrant or Zone Building or other structure Homicide, home invasion, robbery, sexual assault,… Spiral Large area, no barriers, open field Kidnapping, homicide,… Strip or Line Large area looking for large object in a single direction Plane crash, … Grid Large area looking for large object in two directions Arson, …

Collect & Package Physical Evidence Physical Evidence: any and all objects that can establish that a crime has been committed or can provide a link between a crime, victim, and/or perpetrator. Must be handled in a way that prevents any change from scene to lab. Common examples of physical evidence: Fibers/clothing Paint chips, broken glass or chemicals Hair Body fluids Bullets Soil Fingerprints Shoe or tire tracks Tool marks Not a comprehensive list

Evidence, cont. Must be placed in separate containers to prevent cross-contamination Maintain chain of custody (a list of all persons who came into possession of an item of evidence) Obtain controls (physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence) Submit evidence to laboratory

Evidence Submission Form NOTE:

Chain of Custody Form Chain of Custody

Legal Considerations at Crime Scene Under the Fourth Amendment to the United States Constitution, most searches by the police require a search warrant based on probable cause, although there are exceptions. Any police entry of an individual's home always requires a warrant (for either search or arrest), absent exigent circumstances, or the free and voluntary consent of a person with reasonably apparent use of or control over the property.

Legal Considerations at Crime Scene 4th Amendment: 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.

Probable Cause In terms of seizure of items, probable cause merely requires that the facts available to the officer warrants a "man of reasonable caution" to conclude that certain items may be contraband or stolen property or useful as evidence of a crime.

Search Warrants A search warrant is a court order issued by a Magistrate, judge or Supreme Court Official that authorizes law enforcement officers to conduct a search of a person or location for evidence of a crime and to confiscate evidence if it is found. Officers must have a search warrant or they must have one of the exceptions to the Search Warrant Rule.

Exceptions to the Search Warrant Rule Search subsequent to arrest Existence of emergency circumstances Plain View Consent Stop & Frisk/Terry Pat Down Inventory Need to prevent the immediate loss or destruction of evidence Administrative Border Hot Pursuit