Page 24 - A Burning Question Fire Debris

LAB 2
PROCESSING THE EVIDENCE
1. Carefully open your package of questioned
fire debris obtained from the crash site on
Backbone Mountain.
2. Determine which groups will perform which
analysis - three groups will analyze the
evidence samples for the presence of gasoline
and three groups will analyze the evidence
samples for the presence of diesel fuel, as
these are among the most commonly used
ignitable liquids.
3. Analyze the sample in the same manner as
described for the known samples in Lab 1
(NOTE: As both ignitable liquids have a similar
hydrocarbon composition to one another,
a light color change may be observed in
a colorimetric tube in the presence of the
24 THE MYSTERY OF LYLE AND LOUISE
opposite liquid, such as a gasoline colorimetric
tube in the presence of diesel fuel may exhibit a
light green color change at the base of the tube.
This color change, however, will be noticeably
lighter than the positive control ran in Lab 1).
4. Once your analysis of this sample is complete
and you observations have been recorded,
return the evidence to the package and reseal it.
5. Share your results among the remaining
groups.
6. Once evidence analysis is complete, as a group,
determine whether an ignitable liquid was
present in the evidentiary sample collected
from the burned vehicle. Discuss your theories
as to why or why not.