Problems of reliability in the phenotyping of erythrocyte acid phosphatase in bloodstains.

Erythrocyte acid phosphatase is a useful system for the crime laboratory for both fresh and degraded blood and bloodstains, provided the inherent problems of phenotyping this particular enzyme system are recognized. Because of the great number of variables affecting this enzyme system in vitro, phenotyping should not be attempted unless the complete history of origin and handling of the sample is known.