The zinc test as an alternative for acid phosphatase spot tests in the primary identification of seminal traces

The value of the acid phosphatase spot test in the primary visualization and identification of seminal traces is hampered by the sensitiveness of the enzyme to biodegradation. An alternative spot test is proposed, based on the high concentration of the more stable zinc metal in seminal plasma. The proposed zinc spot test is simple and suitable for on site investigation. Although the sensitivity in fresh stains is lower than that of the acid phosphatase spot test, this is largely compensated by the lower sensitiveness to biodegradation. The specificity for semen is higher than that of the acid phosphatase spot test. In vaginal swabs it was nevertheless seen, that samples should be taken within 24 h after alleged sexual assault to give reliable results.     

Evaluation of microbial soil identity in forensic science

Microbiologic analysis of different soil samples was undertaken to assess the value of this method for forensic purposes. Three groups of micro-organisms were isolated on selective media: bacteria, fungi, and actinomycetes. Comparison of the morphology of the colonies led to the conclusion of non identity of the soil samples under examination. The method was applied to soil traces on articles of clothing, trousers, shoes, and stockings. It was found that the soil did not originate from the suspected scene of a crime. Examination of the microbiologic soil composition does not provide an absolute certainty of identity, but it is highly reliable.