Crime Scene Manual Flashcards
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
The ____________________ or _______ test is the test utilized in the DPS Crime Laboratory for the detection of semen.
acid phosphatase or “AP”
Since the acid phosphatase enzyme is present in ___________, ________________ need not be present for a positive reaction.
semen
spermatozoa
This chemical reagent is used to locate latent traces of blood on both porous and non-porous surfaces.
Bluestar
Bluestar should be used in a ____ room.
darkened
When using Bluestar outdoors, ______________.
wait for night
Bluestar should be used to _______________ and ______________ post-offense cleaning of a bloodstained area rather than as purely a presumptive test.
demonstrate and photograph
When spraying Bluestar, apply a _________ of the mixture from a distance of about two feet.
fine mist
_____________ Bluestar will not increase the effectiveness of the mixture.
Over-spraying
To photograph a luminescent response with Bluestar, one should use ____ ________ ____ ________ photography.
Bulb Extended Time
When using Bluestar a _______________ response is presumptive positive for the presence of blood.
luminescent
The use of Bluestar _________________ the testing of evidence for DNA.
will not prohibit
Bluestar has a shelf life of _____ years.
three
Once Bluestar is mixed, it is best used within _____ of production.
three hours
Bluestar __________ be stored after production.
should not
Packaging of bloodstained clothing should be done in order to __________________________________.
to avoid or prevent transfer or alteration
Bloody clothing may be placed on a sterile clothes hanger and _______ __ _____ with all seams taped.
wrapped in paper
If blood soaks through a packaged item of evidence you should__________________________?
not unpackage the item
Remove the evidence tag, repackage the item, then place the evidence tag on the outside of the new paper.
The technique used to collect a portion of a visible biological stain (blood, semen, saliva, etc.) for subsequent crime laboratory DNA analysis:
Discriminate collection of a biological stain.
The technique used to collect a portion of a visible biological stain (blood, semen, saliva, etc) for subsequent crime laboratory (DNA) analysis is:
dampen an individually packaged sterile swab with sterile water, then vigorously scour the portion of the stain to be collected.
Return the swab to its wrapper with the swab end near the opening.
When swabbing a biological stain, one should attempt to obtain a _____________ of the biological material on one portion of the swab rather than allowing _________ of the stain throughout the swab.
concentration / diffusion
The technique used to attempt to collect latent traces of biological material (blood, semen, saliva, etc.) from surfaces upon which its existence is suspected but not apparent or visible.
Indiscriminate collection of biological material.
Collection method the same as discriminate collection.
For pourus surfaces with visible blood stains, it is always best to ___ _ ______ containing the stain when it is not practical or possible to collect the entire item.
cut a swatch
This technique is used to enhance faint pattern transfers in blood on absorbent surfaces.
Tri-Dri Leucocrystal Violet
Leuccrystal Violet (LCV) can create _______________ when applied to bloody pattern transfers which can cause degradation of pattern detail, especially in friction ridges.
bubbles
LCV is preferred for ______________________________ (e.g., carpeting, clothing, paper, etc.).
porous or absorbent surfaces
LCV produces a _____________________ colored reaction when it comes into contact with blood. The background surface color should be considered when deciding to whether to apply LCV.
violet or purple
LCV has a __________________ shelf life. Once mixed, the LCV solution has a ____________ shelf life.
indefinite
30 day
A Tri-Dri Lecocrystal Violet Kit is mixed with one _____ ______ __ ________ ________.
one 16 oz. bottle of hydrogen peroxide
All bloodstains must be _______________ prior to the application of LCV or Amido Black.
dried
Cyanoacrylate fuming may be __________________ to the LCV and the Amido Black process.
detrimental
The ______ detail can normally be achieved by applying the LCV to the faintest patterns.
finest
When applying LCV for footwear patterns, spraying ___________ the last visible pattern will normally produce the best results.
just beyond
If the pattern is comprised of blood, the LCV solution will react within __________ by changing the stain a violet color.
30 seconds
This technique is used to enhance faint pattern transfers in blood on non-porous surfaces.
Amido Black
Amido Black is preferred over Leucocrystal Violet for the ___________ and ___________ of bloody friction ridge detail.
enhancement and development
Caution must be exercised when applying the methanol-based formula to ___________________ surfaces because it may destroy friction ridges and/or other pattern transfers as well as the surface beneath them.
painted or lacquered
Amido Black should not be applied to ______ ________ because it may stain the surface and prevent visualization of any enhanced bloodstain patterns.
porous surfaces
_________________ is preferred over _________________ for the enhancement and development of bloody friction ridges.
Amido Black preferred over Leucocrystal Violet
Amido Black produces a ______ or ____ ____ stain when it comes into contact with blood.
indigo or dark blue
Amido Black has two forms of solutions, ______________ and ___________.
methanol based and water based
Amido Black has an __________ shelf life.
indefinite
Amido Black should be stored at ________________.
room temperature
Amido Black __________ be stored in vehicles for extended periods.
should not
The Amido Black water-based formula is _______ in sensitivity and color intensity to that of the methanol-based formula.
similar
If both LCV and Amido Black are contemplated, ___________ must be sequenced first.
LCV
When using the methanol based Amido Black solution leave the developer solution on the surface for approximately __________ to ________.
30 seconds to 1 minute
When using the water based Amido Black solution leave the developer solution on the surface for approximately __________ to ________.
3 to 5 minutes
A small fan or pressurized air canister may be used to ______ the solutions away from the developed patter.
“push”
Once a pattern has been enhanced with Amido Black, it may then be photographed using ______________________.
Comparison Photography
When burning photos taken with the Nikon D7100 / D7000 camera to a disk, two DVD-R should be created. The first DVD-R created will be labeled ___________________ and should be handled as a piece of evidence. The second DVD-R will be labeled _______________ and should be kept in the investigative file.
1st disk - “Original/Archive Disk”
2nd disk - “Working Disk”
This technique is used to photograph subjects under reduced or limited lighting conditions whenever an exposure under existing light is preferred over the use of the flash and when the proper exposure can only be achieved with a shutter speed that renders hand-held operation of the camera impractical due to camera movement.
Metered Extended Time Exposure
