Investigation of bloodstains: false negative results of the benzidine test

Since the discovery of the Benzidine Test, this method has been considered absolutely reliable for the generic diagnosis of bloodstains. The authors reviewed support the existence of false positive results, as the subtract in the coloration reaction the peroxidases may be found in numerous natural products [ 11. There is also general agreement with the false negative results: a negative result provided by the Benzidine Test indicates that the stain is not blood [2]. Given the strong certainty offered by most works of forensic medicine and criminology, most countries Spain included use this technique as a screening method in the investigation of bloodstains: when the result is negative the i…