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bloodstain, which is then placed on vinyl acetate The evidence collection bags must be labeled
backing. properly with a description of the evidence,
the source location, agency, chain of custody,
Proper evidence packaging is crucial to protect case / item numbers, health hazards, and
against loss, contamination, deterioration, storage conditions (room temperature, frozen,
crosstransfer betwen the samples (suspect/scene/ refrigerated). The protocols for evidence collection
item/ victim), and biohazards. are very detailed and beyond the scope of this
manual, however, it is important to remember that
All biological materials must be completely evidence which is improperly collected may be
dried and placed in their own separate, correctly suppressed in court, which may cause the case to
labeled, paper bags. Plastic bags are only used be dismissed.
for transporting moist blood evidence for no
more than two hours. If moist biological evidence After the evidence is collected and transported to
is left in any plastic container there is a great the lab, a confirmatory test must be performed.
possibility of microorganism growth which Confirmatory tests are often microcrystalline
may alter the evidence, degrade DNA, and/ tests that are based on the formation of
or inhibit future testing. Collected bloodstains hemoglobinderived crystals under heated
should be refrigerated, unless the bloodstain conditions. Microcrystalline tests involve the
was found in soil, then it should be frozen so that addition of specific chemicals to blood so that
microorganisms present will not degrade the DNA. crystals with hemoglobin derivatives will be
16 THE MYSTERY OF LYLE AND LOUISE
