False Positive Semen Detection Test Results By Acid Phosphatase Alone

Semen and Sperm Detection test report on a semen detection with negative Prostate Specific Antigen (PSA), positive Acid Phosphatase (AP) and negative for sperm identification.

Other Tests     Semen Detection Statistics

Two halves of two different feminine pads were received from Norway.  The client ordered multiple DNA extractions however we contacted the customer and recommended the semen detections first.  Both samples were positive for AP and there was no PSA present or sperm heads present.  Since the semen detection was negative the customer saved hundreds of dollars for the DNA extractions he initially ordered.

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(Report is identical to released notarized report except customer information was removed)

Analysis Report

Case #  PSA81986A-B

Evidence

Item A was a white feminme pad cutting size 2.125 by 1.75 inches marked #3 Person C.  Item B was a white feminme pad cutting size 2.125 by 1.50 inches marked #4 Person D.  UV long and short wave light confirmed the locations for testing.

Analysis

A test for the presence of Acid Phosphatase (AP) was conducted.  Acid phosphatase is an enzyme present in semen at concentrations of 20 to 400 times other body fluids.  The presence of acid phosphatase is a presumptive test for the presence of semen and needs to be confirmed by DNA or the presence of a Prostate Specific Antigen (PSA).  

A Prostate Specific Antigen (PSA) test was completed.  The detection of the PSA on forensic samples is often helpful because it confirms the presence of semen even in samples that involve vasectomized or azoospermic individuals. The PSA is a glycoprotein produced by the prostate gland and secreted in seminal fluid at concentrations (from 2.0x105 to 5.5x106 ng/ml).

A microscopic examination was completed.  Microscopic examination is a presumptive test for the presence of sperm unless intact, non-degraded sperm are detected.  Intact sperm are rarely visible after 4 days unless the sample was immediately frozen and properly stored.

Results

Both items tested negative for semen.  The PSA tests were negative and no whole sperm heads were detected microscopically.  The AP tests were positive on both samples.  The Acid Phosphatase test is presumptive and is used only to determine the amount of semen in the sample when the PSA is positive.

Conclusions

Items A and B tested negative for the presence of semen by PSA, and microscopic inspection.  It is unlikely that copulation has occurred within 5 days of either sample being worn.  Samples and proof of test will be held in freezer for 90 days then destroyed.  Report issued to address below.