ForensicBio:SexualAssualt

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

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/swabbing2. laser capture microdissection

Who collects sexual assault kit samples?

ER doctorsMESANE nurses (Sexual Assualt Nurse Examiner)Most major hospitals

How long do Sexual Assault kits take to collect?

1-4hours

How long does it take to analyize a kit?

several hours to several months

How long are the kits retained?

Until the case has been adjudicateduntil statue of limitaions has expiredindefinietly in homicide casesmaybe discarded sooner if victims requests or if case isnt reported to police

What are the steps?

Control swabs Toxicology testing Known blood sample Oral swabs/smearsFingernail scrapingsForeign material collectionsclothing collectionsbitemarkshead/pubic hair combingshead/pubic hair standardsgenital,perianal, vaginal and anal swabs and smears

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

Studies show that ____% of rapists do not ejaculate after _____ minuites of vaginal penetration

15%30-60minutes

The vagina is a ___ enviornment

sperm hostile

the cervix is a ______ environment

Sperm friendly

T/F Semen identified on anorectal swabs indiacts anal penetrationTrue False

FALSE:�Could be a result of contamination from vaginaldrainage �Could be due to collection technique wheninserting swabs into the rectum

What factors effect PCI?

Stage in menstrual cyclewashing/urinating/defacating/eatingMovementcollection techniquewashings, swabs, smears, liquid salivadeathtemp and humidity