Determination of the amount of human DNA in a stain will indicate the probability of obtaining a full STR profile and is thus critical for investigation of sample identification. Contrary to other findings, this study demonstrates that luminescent presumptive tests affect the amount of the sample DNA after a few months, leading to DNA degradation. However, with extremely small samples or when testing large numbers of samples, it may be necessary to expose the potential bloodstains directly to presumptive tests, and these also save time and money by prioritizing the samples sent for serological tests and DNA analysis.