1. Science of Crime Scenes
Chapter 4.2
Science of Crime Scenes

2. Science of Crime Scenes
Chain of custody
It is a document that records the movement of every item of evidence from its moment of collection to its ultimate disposal
The chain of custody can be defined as the order of places where, and the persons with whom, physical evidence was located from the time it was collected to its submission at trial
Any break in the chain could prove disastrous for that item of evidence’s use in court
Where was it? Was it tampered with? Where was it? Who had access to it? Could it have been contaminated?
Science of Crime Scenes

3. Handwritten chain of custody
Science of Crime Scenes

4. Electronic chain of custody
Science of Crime Scenes

5. Science of Crime Scenes
Chain of custody
It is also the source of the authentication or identification of real evidence, i.e., proving that an item of evidence is genuine
Federal Evidence Rule 901(a) codifies this requirement:
''The requirement of authentication or identification as a condition precedent to admissibility is satisfied by evidence sufficient to support a finding that the matter in question is what its proponent claims."
Before physical objects are admissible in evidence the proponent must establish that they are in "substantially the same condition as when the crime was committed.*"
Science of Crime Scenes
*Gallego v. United States, 1960

6. When is something in your custody?
Samples and data are considered to be in your custody when:
They are in your physical possession.
They are in your view, after being in your physical possession.
They are in your physical possession and then secured so that tampering cannot occur.
They are kept in a secured area, with access restricted to authorized personnel only
Science of Crime Scenes

7. How could anybody get this wrong?
Let’s follow an item of physical evidence as it travels from the crime scene through many hands before it finally ends up in court…
Science of Crime Scenes

8. Science of Crime Scenes
First it is collected at the scene (1) and handed off to the detective by the CSI (2), who submits it to the evidence clerk at the laboratory (3).
The clerk transfers the evidence to the vault (4), from which four scientists retrieve the item of evidence for each of their analyses (5–8), returning it after they are done (9–13).
When all exams are completed, the evidence is taken from the vault by the clerk (14) and returned to the detective for storage (15) until trial when it is presented in court (16).
In this hypothetical example (chain of custody protocols vary by jurisdiction), this one item of evidence has 16 exchanges associated with it, all of which must be documented
Science of Crime Scenes

9. Problems with Chains of Custody
The first and probably greatest problem is inappropriate packaging: When evidence is recovered it must be protected against deleterious change
Packages that are inadequately sealed are another potential problem
Losing recovered items or having them be unaccounted for is another potential problem at the crime scene or even later
Science of Crime Scenes

10. Chain of custody is central to all crime scenes
Maintaining the chain of custody can take a lot of time but “Mediocrity is always in a rush; but whatever is worth doing at all is worth doing with consideration. For genius is nothing more nor less than doing well what anyone can do badly.” (Amelia E. Barr)
Science of Crime Scenes