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Collection of Rape Evidence

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Presentation on theme: "Collection of Rape Evidence"— Presentation transcript:

1 Collection of Rape Evidence
Serology Unit

2 Summary Rape is often associated with many different forensic crime scenes 293,066 crimes are reported annually (ages 12 and older) Equal to a sexual assault every 107 minutes 68% of sexual assault was never reported to the police 98% of rapists will never spend a day in prison

3 Testing for Seminal Stains
Seminal stains may indicate that a rape has occurred as well as potentially identify a victim or suspect Older methods (looking for greater traces) were proven to be insignificant Best way to find seminal stain is the acid phosphatase color test

4 Acid Phosphatase Test Acid Phosphatase – enzyme that is secreted by the prostate gland into seminal fluid. This enzyme will react with an acidic solution of sodium alpha naphtylphosphate and Fast Blue B dye. 4-methyl umbelliferyl phosphate (MUP) will fluoresce under UV light when in contact with the enzyme.

5 Acid Phosphatase Test Process
Moisten a piece of filter paper and rub it over the suspected stain area. This transfers any acid phosphatase present. Place a drop or two of the sodium alpha naphthylphosphate and the Fast Blue B solution on the paper. Look for purple stains on the paper. This will indicate an area with acid phospatase. Collect sample from stain to analyze DNA.

6 Acid Phosphatase Test For large garments or pieces of fabric the fabric can be broken down into sections for testing Large filter paper can also be placed over the fabric and sprayed with MUP. Using a black light you can visualize stains by looking at fluorescent stains. Could come up a false positive (some veggies, fungi, etc.) Seminal stains usually show up in 30 seconds or less.

7 Collection of Rape Evidence
Collection of rape evidence includes noting bruises, blood, or injuries, and collecting foreign hairs, fibers, blood, or semen. These all help forge a vital link of circumstances surrounding a sexual crime The victim then must go through a long careful process to find and preserve any evidence transferred.

8 Collection of Rape Evidence
Process Place a clean bed sheet on the floor and lay paper over it. Have victim take off shoes and then stand on top of the piece of paper and carefully remove clothing. The paper on the floor will pick up any pieces of loose evidence. The clothing must then be placed into separate paper bags and folded over so as to not cross-contaminate. The paper sheet will then be folded and placed into a paper bag. If any other material such as sheets or other clothing were involved they will also be sealed and sent to the lab. The lab will then look for seminal fluid and carefully analyze for DNA matches.

9 Collection of Rape Evidence
Process continued… The rape victim will undergo a medical examination as soon as possible after the assault. The trained personnel will then collect the appropriate physical evidence using a victim rape collection kit from the forensic laboratory. The findings of the kit are on pages in the book. Make sure to write in your notes.

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