Crime Scene Manual Flashcards
(188 cards)
This technique is used to test stains for the presence of proteins found in blood.
Hemastix - Presumptive Test for Blood
When using Hemastix, a positive response indicates the suspected stain is ______________________________.
possibly comprised of or contains blood
Hemastix ____________________ distinguish human blood from the blood of animals.
cannot
False positive results are possible.
When using Hemastix _____________ results are possible.
“false positive”
Hemastix has a shelf life of ________________.
Approximately One year
While using Hemastix beyond the expiration date will not produce “______________” results, it may produce “______________” results.
will not produce “false positive” results
may produce “false negative” results
As a general practice, Hemastix should be __________ or used only for training beyond the date of expiration.
discarded
Before being used to perform test(s) upon questioned stains, the Hemastix reagent should be tested _______________________.
against a known human blood standard
A control test should be conducted whenever test strip(s) from a new container are used _______________________________ or if ______________________________________________.
for the first time or if more than 24 hours has elapsed since a control test was performed for a previously used container.
Testing with Hemastix will likely __________________ the appearance of the stain being tested.
change
A stain should be photographed prior to testing if its _______________ may be relevant to the investigation.
characteristics
Hemastix is very sensitive; therefore, it is only necessary to transfer _______ of the stain onto the swab.
a trace
When testing with Hemastix, a positive result is indicated by the immediate appearance of a __________ color on the pad.
blue-green
When using Hemastix, if the color change is _____________ (within 1-2 seconds), the result is negative.
not immediate
If a Hemastix test result is not “immediate” (1-2 seconds) then there is not a _______________.
positive result
The pale yellow pads at the ends of the strips ore impregnated with the chemical compound ___________________, which is a blood reagent commonly used in liquid form to perform presumptive tests at crime scenes.
tetramethylbenzadine
The chemical components of the Hemastix ________________ with DNA analysis.
do not interfere
The two techniques used to test stains for the presence of the acid phosphatase enzyme present in human semen utilized by the Texas Rangers are the _____ ______ _____ _______ and the _________ _________.
Peavy Seminal Fluid Dischap - Presumptive Test for Semen
and
Arrowhead Forensics
When using Peavy Seminal Fluid Dischap, a ________________ response indicated the probable presence of semen.
positive (purple color)
When using Peavy Seminal Fluid Dischap the color change should occur within a few seconds (__________), color change may not be immediate.
30 seconds
any color change after 30 seconds should be disregarded
When using Arrowhead Forensics, a ________________ response indicated the probable presence of semen.
deep purple
The acid phosphatase reagent ampoule _______________ be applied directly to the suspected semen stain.
should not be
The acid phosphatase testing will __________ change the appearance of the stain being tested.
likely
When using either the Peavy Seminal Fluid Dischap or the Arrowhead Forensics, a stain should be _____________ prior to testing if its characteristics may be relevant to the investigation.
photographed