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Published byKerrie Reeves Modified over 9 years ago
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Forensic Characterization of Semen The presence of seminal stains is important in crimes involving sexual offenses. The presence of seminal stains is important in crimes involving sexual offenses. Two steps: 1. Stains must be located 2. Stains are tested to determine identity
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Testing for Seminal Stains Stains can sometimes be identified visually. Stains can sometimes be identified visually. Acid phospatase test- Acid phosphatase is an enzyme found in large concentrations in semen. Acid phospatase test- Acid phosphatase is an enzyme found in large concentrations in semen. 2 tests: 1. Acid phophatase reacts with sodium alpha naphthylphospate and Fast Blue B dye to give a purple color. 2. Acid phospatase reacts with 4-methyl umbelliferyl phosphate, which fluoresces under UV light
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Testing for Seminal Stains Microscopic Examination- Semen can be identified by the presence of spermatozoa Microscopic Examination- Semen can be identified by the presence of spermatozoa Prostate Specific Antigen – antigen/antibody reaction confirms the presence of seminal fluid Prostate Specific Antigen – antigen/antibody reaction confirms the presence of seminal fluid
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Collection of Rape Evidence Evidence of rape is not limited to semen Physical injuries Physical injuries Blood Blood Hairs Hairs fibers fibers
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Collection of Rape Evidence Physical evidence collected from a rape victim include: Pubic combings Pubic combings Pubic hair reference samples Pubic hair reference samples External genital dry- skin samples External genital dry- skin samples Vaginal swabs Vaginal swabs Cervix swabs Cervix swabs Rectal swabs Oral swabs Head hairs Blood sample Fingernail Scrapings Clothing Urine specimen
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Collection of Rape Evidence If a suspect is apprehended, the following physical evidence would be collected. Clothing Clothing Pubic hair combings Pubic hair combings Head and pubic hair samples Head and pubic hair samples A penile swab A penile swab Blood sample or buccal swab Blood sample or buccal swab
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