Honors Forensic Science. Crime Labs “run” on physical evidence Physical Evidence = any and all...

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The Crime Scene Honors Forensic Science

Transcript of Honors Forensic Science. Crime Labs “run” on physical evidence Physical Evidence = any and all...

Page 1: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

The Crime SceneHonors Forensic Science

Page 2: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

I. Processing the Crime Scene

Crime Labs “run” on 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 and its victim or a crime and its perpetrator

Page 3: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

To be effective, evidence must be:

Recognized Collected and processed properly

Collector must be selective using knowledge of crime lab techniques, capabilities and limitations

Page 4: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 5: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Crime labs do not solve crimes

Many jurisdictions have specialized teams to conduct crime-scene searches

Not all crime scenes require retrieval of physical evidence

Page 6: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

II. Secure and Isolate Crime Scene

First officer(s) on scene should:

Provide medical assistance, if needed, to victims

Arrest perpetrator if present Preserve and protect area as much as

possible

Page 7: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

II. Cont’ d

Exclude all unauthorized personnel from scene

Isolate area using ropes, tape, barricades, guards, etc.

Page 8: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Lead Investigator should:

Determine boundaries Determine perp’s path of entry and exit Document obvious items Conduct initial walk-through Develop examination strategy

Page 9: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Record the Scene

Must document the crime scene in original state

Information used in investigation and in court

Monetary limitations may determine method used to document the scene

Page 10: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Photography Must be in unaltered condition Crime scene photographed completely Items of physical evidence

photographed to show position and location; close-ups to show detail

If size is important, include a measurement scale in photo for reference

Page 11: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Videography Can be used to augment photography Can narrate events on videotape Does not replace photography

Page 12: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Sketches

Rough Sketch

Containing an accurate depiction of the dimensions of the scene and showing the location of all objects having a bearing on the case

Page 13: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Rough sketch should include; Recovered items of physical evidence Distance measurements of items (use 2

fixed points) Legend Compass heading designating north

Page 14: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Finished Sketch

A precise rendering of the crime scene, usually drawn to scale

Often prepared with aid of templates and drafting tools

Reflect same information as rough draft

CAD programs often used

Page 15: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 16: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Notes

Must be a constant activity Should include detailed written

description of scene Detailed description of evidence:

location of items, time item discovered, by whom, how and by whom it was packaged, etc.

Page 17: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Notes often only written record of details

Tape-recording can be advantageous, but still should be transcribed into a written document

Page 18: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Conduct Systematic Search

Thorough and systematic, even if seems unnecessary at the time

How crime scene is searched depends on type of crime, local and size of scene, # of collectors, etc.

Page 19: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 20: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Collect massive objects to microscopic traces

Important to collect possible carriers of trace evidence as well as obvious items

Portable vacuum cleaners helpful

Medical examiner may also provide evidence

Page 21: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 22: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Medical examiner may collect and forward: Victim’s clothing Fingernail scrapings Head and pubic hairs Blood (for DNA typing) Vaginal, anal, and oral swabs Recovered bullets from body Hand swabs from shooting victims

Page 23: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Collect and Package Physical Evidence

Prevent change

Change can arise from contamination, breakage, evaporation, accidental scratching or bending, or loss through improper or careless packaging

Maintain evidence in original condition if possible

Page 24: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Each different item or similar items collected at different locations must be placed in separate containers. Packaging evidence separately prevents damage through contact and prevent contamination

Page 25: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Maintain Chain of Custody

Chain of custody – list of all persons who came into possession of an item of evidence

Must be established whenever evidence is presented in court

Adhere to standard procedures Keep to a minimum

Page 26: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Obtain Controls

Examination of evidence often requires comparison with known standard or control

Control = physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime scene evidence

Page 27: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Quality and quantity of controls may help determine evidential value of crime-scene evidence

Controls must be treated with equal care as actual evidence

Page 28: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 29: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Submit Evidence to Lab

Usually submitted personally or by mail shipment

Must be accompanied by evidence submission forms

List of tests to be performed on each item

List of items submitted

Page 30: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.
Page 31: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Crime Scene Safety

International Association for Identification Safety Committee Gloves Particle masks/respirator, goggles, face

shield Be alert to sharp objects Use biohazard bags Note taking done with uncontaminated

gloves No eating, drinking, smoking, etc. at

crime scenes

Page 32: Honors Forensic Science.  Crime Labs “run” on physical evidence  Physical Evidence = any and all objects that can establish that a crime has been committed.

Legal Considerations

Fourth Amendment – Prohibits unreasonable search and seizure

Mincey v. Arizona Michigan v. Tyler When time and circumstances

permit, obtain a search warrant before investigating and retrieving physical evidence at crime scene