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

In 2009, the Norwegian police academy educated their first crime scene dogs, trained to locate traces of seminal fluid and blood in outdoor and indoor crime scenes. The Department of Forensic Biology was invited to take part in this project to educate the police in specimen collection and presumptive testing. We performed tests where seminal fluid was deposited on different outdoor surfaces from between one hour to six days, and blood on coniferous ground from between one hour to two days. For both body fluids the tests were performed with three different volumes. The crime scene dogs located the stains, and acid phosphatase/tetrabasebariumperoxide was used as presumptive tests before collection for microscopy and DNA analysis. 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 32h, 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 32h. The presumptive tests confirmed the dog's detection. We were able to get DNA results for most stains in the timeframe 1-48h with the two largest volumes. The smallest volume shows diversities between the parallels, with no DNA results after 24h. 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 24-48h. Other parameters that should be taken into account are the weather conditions, type of surfaces and specimen collection.