Detecting and collecting traces of semen and blood from outdoor crime scenes using crime scene dogs and presumptive tests

For seminal fluid the dogs were able to locate all stains for up to two days and only the largest volume after four days. The presumptive tests confirmed the dog's detection. By microscopy we were able to detect spermatozoa for the smallest volumes up to 32 h, and for the largest volume up to 4 days, and the DNA results are in correlation to these findings. For blood all the stains were detected by the dogs, except the smallest volume of blood after 32 h. The presumptive tests confirmed the dog's detection. We were able to get DNA results for most stains in the timeframe 1-48 h with the two largest volumes. The smallest volume shows diversities between the parallels, with no DNA results after 24 h. These experiments show that it is critical that body fluids are collected within a timeframe to be able to get a good DNA result, preferably within the first 24-48 h. Other parameters that should be taken into account are the weather conditions, type of surfaces and specimen collection.