Title: Forensic Evidence - Criminal Defense Wiki
Headings: Forensic Evidence
Forensic Evidence
Contents
Background
Basic Principles of Forensics
Law of Exchange
Transfer/ Trace Evidence
Primary (Original) Transfer
Secondary Transfer
Examples of Primary vs. Secondary Transfers
Chain of Evidence/ Custody
Contamination
Investigation and Evaluation Procedures
Scene of Crime
The Collection of Evidence
The Autopsy
Specific Physical Evidence to Consider in Homicide Cases
Bruising
Cuts
Internal Wounds
Establishing Identity
Testing Physical Evidence
Homicide Tools
Blunt and Sharp Edged Objects
Weapons of Strangulation
Cars as Weapons
Challenging the Prosecution’s Case
Evaluating the Presence or Absence of Physical and Forensic Evidence
Source v. Identity
The Absence of Evidence
Missing evidence due to failures to properly collect relevant evidence or do necessary testing
Lack of expected evidence, given the circumstances alleged by the prosecution and witness testimony
The Critical Importance of Discovering and Utilizing Material Evidence in Defense of a Criminal Case
Conclusion

Content: In beating a woman, a criminal has her blood on his hands from the assault (primary). After the assault, our client approaches the victim in an attempt to help her; he touches her body and as a result has the victim’s blood on his hands (secondary). Chain of Evidence/ Custody
Chain of custody refers to the sequence of events of a piece of evidence as it goes from the place where it is initially found (scene of the crime) up until the time it appears in court. Think of this as an actual chain, with pieces that are connected. Every part of the chain should be documented - from discovery at the crime scene, through evidence gathering, storage, lab analysis, return to storage, transfer to court, etc. The purpose of such documentation is to ensure that the evidence offered by the prosecution is the same thing the investigators seized, and that it has been in possession of, or secured by, a responsible person at all times. By thus evaluating the chain of custody, one can make certain of its integrity. Every link should be documented by date, time, person handling the evidence, what was done with the evidence by that individual, what tests were performed and where. In many cases there will be gaps in the chain of custody;