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Bureau of Criminal Apprehension

A Division of the Minnesota Department of Public Safety

BCIP (Semen)

Suspected semen stains, usually found with the use of an alternate light source, can be screened at the crime scene by use of the BCIP (5-bromo-4-chloro-3-indolyl phosphate) reagent.  In this presumptive test, the BCIP reagent reacts with prostatic acid phosphatase, a constituent of semen, to give a blue or aqua color reaction.  A blue color change is a positive reaction and is indicative of the presence of semen.

The image below shows a positive BCIP test on the left and a negative test on the right.

positive and negative BCIP test