8127/frame/fm

 
f.
Documentation
Both the scene(s) and the evidence must be documented rigorously throughout
the process. This serves a number of functions. First, the condition of the scene
as it was initially found is recorded. It is also important to document the scene
as it is altered by the search for and collection of evidence. Finally, pictorial
documentation, in particular, may record details that were overlooked when
the scene was initially processed. It is not unusual for some feature of the
evidence or an element of the scene to become important at a later date.
 
i.
Chain of custody.
The whereabouts and handling of each item of evi-
dence must be documented from the time it was collected through the time
it is tested, consumed, or destroyed. Inattention to detail in the 
 
chain of
custody
or 
 
chain of evidence
may disqualify otherwise good work from admis-
sion at trial. More importantly, from a scientific perspective, a break in the
“chain” inescapably weakens any potential association between that evidence
item and another. It leaves open the possibility of malicious or adventitious
alteration of the evidence during the gap.
For example, in one case, a malicious alteration of the “chain” prevented
admission of a large amount of otherwise perfectly good DNA results.
In one such case, all of the DNA evidence was excluded because of a com-
pletely unnecessary break in the chain. A reference blood sample was taken
from a suspect accused of murder to compare with evidence in the case. By
comparing the dates on the paperwork, an inconsistency was detected
between when the suspect was taken to have the reference sample drawn
and when it was logged as evidence. When confronted with this conundrum,
the detective admitted on the stand that he had inserted an expedient date
into a report written only after the fact. Although he probably never
intended to mislead anyone, he also failed to appreciate the purpose of a
chain of custody. The suspect was convicted without the DNA evidence,
but it needn’t necessarily have been so.
Confusion, fatigue, or haste may also lead to inadvertent breaches of writ-
ten documentation. We are all familiar with the doubt created when Dennis
Fung and Andrea Mazzola collected samples as a “team” at the 
 
Simpson
crime
scenes and neglected to mark sample envelopes properly with the initials of
the person who physically collected the sample (
 
People v. Simpson
, April 27).
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Good Field Practice — Processing a Crime Scene
207
A criminalist found himself in an odd chain-of-custody predicament
created by changing jobs. While employed at a city crime laboratory, he
received a case that could only be analyzed at the state crime laboratory,
where he had previously been employed. At one point, he checked out evi-
dence to himself from the jurisdiction of origin, the city, where he was then
employed, and took it to the state laboratory where he analyzed it. The analyst
did not consider the movement of the evidence to be external to the city
jurisdiction because he was the one analyzing it. Through some accident of
logic, he properly documented the “external” chain of custody on the enve-
lope containing the reference stain, but not in his notes. This created, in the
documents that the defense received at least, a breach of the chain of custody.
By the time the case went to trial, the analyst had already transferred back
to the state laboratory, further confusing the issue. The circumstances were
successfully explained at trial, but this story emphasizes that one can never
be too meticulous about documentation. The details count.