Investigating the Crime Scene

1. Chapter 1 Investigating the Crime Scene

2. Objectives Students should gain an understanding of: The steps taken to preserve a crime scene Documentation of the crime scene Ways to systematically search the crime scene Methods for collecting, preserving, identifying, packaging, and transporting evidence The chain of custody The Fourth Amendment and its application to the search and seizure of evidence

3. Introduction Collection and preservation of evidence are essential for successful criminal investigation Failure to assure proper collection and preservation can jeopardize the investigation Accurate records are needed of the actions taken by investigators Physical evidence is usually collected by the police or civilian crime scene technician; it includes any and all relevant materials or objects associated with the crime scene, victim, suspect, or witness

4. Securing the Crime Scene (1 of 3) First responder Offer assistance to injured persons May exclude nonessential persons from the crime scene Later responders Are responsible for security of crime scene Limit access: All who enter have potential for contamination

5. Securing the Crime Scene (2 of 3) Identifying, establishing, protecting, and securing the boundaries Set initial boundary larger than the scene Document all actions and observations: State of scene Existing conditions Personal information Actions and statements of persons entering and exiting Items moved and who moved them

6. Securing the Crime Scene (3 of 3) Identifying, establishing, protecting, and securing the boundaries Preserve physical evidence for later identification, collection, and submission Create single path in and out of scene Identify all personnel at scene

7. Documenting the Scene and the Evidence (1 of 9) Documenting is the most important and time-consuming activity at the scene Maintaining chain of custody proves nothing was altered. It demonstrates who discovered an item, when it was discovered, and the item�s appearance, control, movement. It helps the analyst understand how the evidence relates to the overall scene. The investigator should record facts that corroborate, refute, or modify the hypothesis.

8. Documenting the Scene and the Evidence (2 of 9) Note taking Document core of crime scene and physical evidence Make notes in ink, in a bound notebook, with pages numbered sequentially Do not erase errors; cross them out with pen Make notations in chronological order

9. Documenting the Scene and the Evidence (3 of 9) Note taking Evidence documented in notes: Condition Time of discovery Name of discoverer Placement, collection, packaging, labeling Photographs must be documented Audio recordings may be used, but later transcribed

10. Documenting the Scene and the Evidence (4 of 9) Photography Take photos without disturbing elements of the scene Take a systematic series of photos to record the crime scene Photograph as thoroughly as possible Use a 35-mm single-lens reflex camera Retain the original digital images

11. Documenting the Scene and the Evidence (5 of 9) Items included in the photo log: Date and time Camera settings Film roll number and exposure number File name and exposure number Type of shot Distance to the subject Brief description

12. Documenting the Scene and the Evidence (6 of 9) Sketching Accurately record distances between objects Make rough sketches not drawn to scale, but with adequate information for later finishing Sketch the scene from an overhead view Must establish two fixed points that are permanent objects Recognize that a computer professional will prepare finished sketches later using CAD software

13. Documenting the Scene and the Evidence (7 of 9) Items included in a sketch: Case identifier Date, time, location Weather and lighting conditions Name of the sketch Identity and assignments of personnel Dimensions and layout Measurements and positioning Key or legend Orientation Scale

14. Documenting the Scene and the Evidence (8 of 9) Sketching: three techniques Triangulation: measures location of the evidence from fixed points Baseline: draws a line between the fixed points and measures the distance to the evidence at a right angle from this line Polar coordinate method: uses a transit or compass to measure the angle from the north and the distance to the evidence

15. Documenting the Scene and the Evidence (9 of 9) Videography May be used to complement still photography Is the best way to document the overall view of the scene Allows forensic scientists to understand the scene at a later time Record locations of evidence in still photos Record running audio narrative

16. Systematic Search for Evidence (1 of 3) Methodically search for less obvious pieces of evidence Search patterns: Spiral: no physical boundaries Grid: large outdoor crime scene Strip: outdoor crime scene where coordinator organizes many searchers Zone: indoor crime scene where different teams are assigned small areas Wheel: circular crime scenes

17. Systematic Search for Evidence(2 of 3) Search suspected points of ingress and egress Collect evidence that might degrade first Search outside scenes in daylight if possible

18. Systematic Search for Evidence(3 of 3) Recognition of physical evidence First step in processing is to recognize obvious pieces of physical evidence Ability to recognize what is and is not evidence is learned through experience Many departments employ specialized evidence retrieval technicians The nature of the crime determines the type of evidence sought

19. Collection, Preservation, Inventory, and Transportation of Physical Evidence (1 of 4) Once documented, evidence must be collected, preserved, inventoried, and packaged in preparation for submission to the crime lab Physical evidence from scene is a questioned sample Known samples come from relevant persons and are used for comparison Individualization means proving a particular unknown sample is unique

20. Collection, Preservation, Inventory, and Transportation of Physical Evidence (2 of 4) Impression evidence Developed or enhanced by use of specialized photographic techniques or chemical developers Biological evidence Enhanced/developed by chemical means Firearms and ammunition Located by sight Must be rendered safe Store in paper envelopes, bags, or cardboard boxes Make no permanent markings on weapons

21. Collection, Preservation, Inventory, and Transportation of Physical Evidence (3 of 4) Arson and bomb evidence Locate by sight and smell Place carpet, wood, and absorbent materials in clean paint cans and seal lid Place flammable liquids in glass bottle with tight-fitting lid Chemicals and controlled substances Locate by visual observation

22. Collection, Preservation, Inventory, and Transportation of Physical Evidence (4 of 4) Trace evidence May be extremely small or microscopic Collect by forceps, tweezers, scraping, taping, or vacuuming Document and collect questioned and known samples Work in conjunction with medical examiner for homicide evidence collection

23. Packaging Evidence Package must preserve and protect evidence Paper envelopes are routine DNA in blood will degrade if not stored properly Wet blood should dry first and then be scrapped or collected on a swab Put clothing in large paper sacks Take entire piece of evidence as it is found at the scene, if possible

24. Submitting Evidence to Crime Laboratory Evidence is stored in constantly guarded evidence collection areas. It may be submitted to the crime lab in person or via mail. A Federal Firearms License required for postal mailing of firearms. Chemicals, radiological agents, and explosives may be transported via UPS or FedEx. Each item must be packaged separately.

25. Chain of Custody In court, all evidence will be subject to questions about chain of custody. The chain starts with the evidence�s original discoverer. The chain is broken if movements are not documented; that may result in evidence being excluded in court. Preserve the chain of custody by making sure that investigator notes completely document everything that happens to each piece of evidence at the scene.

26. Criminal Evidence and the Fourth Amendment (1 of 5) Evidence is most often excluded due to Fourth Amendment violations. Officers must present an affidavit of probable cause that criminal activity is taking place at a particular location to receive a search warrant. Contraband, �fruits and instrumentalities of the crime,� evidentiary items, voice and handwriting samples, and conversations can all be obtained via warrants.

27. Criminal Evidence and the Fourth Amendment (2 of 5) Exceptions to the Fourth Amendment Border searches: customs searches at the border do not require a warrant Consent searches: persons can voluntarily submit to a search Search incident to arrest: persons and the area under immediate control can be searched during a lawful arrest Plain view doctrine: officers can seize contraband and evidence that they can see from legal vantage point

28. Criminal Evidence and the Fourth Amendment (3 of 5) Exceptions to the Fourth Amendment Emergency exceptions: officers can enter premises without a warrant if they have reasonable suspicion that an injured person is inside Open fields: no expectation of privacy Stop and frisk: officer may pat down a suspicious person who may be armed and dangerous Vehicle inventories: may need to search the vehicle immediately if the driver or other occupant is arrested

29. Criminal Evidence and the Fourth Amendment (4 of 5) Mincey v. Arizona (1978) Police conducted an undercover raid of a suspected drug house. An officer and three suspects were shot. The premises were searched extensively over 4 days without a warrant. The court overturned the conviction: The offense did not merit a warrantless search because the evidence would be not lost while a warrant was obtained.

30. Criminal Evidence and the Fourth Amendment (5 of 5) Michigan v. Tyler (1978) It involved a fire at a furniture store. Investigators conducted several searches, including some well after the fire was out. The convictions were overturned: The later warrantless entries were not part of the initial emergency circumstances. Officers must obtain a search warrant before they conduct a careful, detailed examination of a crime scene.