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Actual sperm released from a substrate may be as low as ______ of sperm deposited in stain
10-15%
Certain substrates, such as cotton, hold on to sperm better than others
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What are the 2 techniques for generateing a DNA profile from stained slides?
1. xylene bath to remove coverslip/mounting mediua, tranfer bio material to extraction tube by scraping/swabbing
2. laser capture microdissection
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Who collects sexual assault kit samples?
- ER doctors
- ME
- SANE nurses (Sexual Assualt Nurse Examiner)
- Most major hospitals
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How long do Sexual Assault kits take to collect?
1-4hours
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How long does it take to analyize a kit?
several hours to several months
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How long are the kits retained?
- Until the case has been adjudicated
- until statue of limitaions has expired
- indefinietly in homicide cases
- maybe discarded sooner if victims requests or if case isnt reported to police
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What are the steps?
- Control swabs
- Toxicology testing
- Known blood sample
- Oral swabs/smears
- Fingernail scrapings
- Foreign material collections
- clothing collections
- bitemarks
- head/pubic hair combings
- head/pubic hair standards
- genital,perianal, vaginal and anal swabs and smears
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Why is time since intercourse important?
- -When IDing the presence of semen isnt enough
- -a consensual partern may be a factor
- -sperm cells can be unrealted to assualt
- -aides in establishing time/circumstances of death
-
Typical post-coital interval (PCI)
intact sperm in vagina
<24 hours
-
PCI sperm heads
~2-3 days
-
PCI sperm heads in cervix
~4-6 days
-
PCI P30 in vagina
<24 hours
-
PCI AP in vagina
~14-48hours
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Studies show that ____% of rapists do not ejaculate after _____ minuites of vaginal penetration
15%
30-60minutes
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The vagina is a ___ enviornment
sperm hostile
-
the cervix is a ______ environment
Sperm friendly
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T/F Semen identified on anorectal swabs indiacts anal penetration
FALSE:
- –Could be a result of contamination from vaginal
- drainage
- –Could be due to collection technique when
- inserting swabs into the rectum
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What factors effect PCI?
- Stage in menstrual cycle
- washing/urinating/defacating/eating
- Movement
- collection technique
- washings, swabs, smears, liquid saliva
- death
- temp and humidity
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