Usually in rape cases, the seminal stains recovered on fabrics are one of the most significant evidence. The stained clothing’s mainly undergarments and swab’s on fabric material recovered from the vagina and surrounding regions are in the first place submitted for DNA fingerprinting test. It is done to make comparison with the blood sample of the person implicated in the case.
For most of the time, it becomes difficult to isolate DNA from stains especially when the stains are old. It happens due to the degradation or decomposition of the biological material obtained depending on the environmental conditions as well. Other possible factors depend on the nature of the clothing. In a recent study, it was observed that maximum DNA recovery was from cotton clothing’s even when stored for long durations followed by tricot material.
DNA fingerprinting has now become the most powerful technique and is widely used across the entire globe today. This is a helpful tool in ascertaining the identity of an individual. For justice community, it has come as a great help. DNA being somatically stable and resistant to environmental degradation has made it a unique tool to be used in forensic medicine.
“Criminalistics is the definitive source for forensic science because it makes the technology of the modern crime laboratory clear to the non-scientist. He delves into the role of comprehensive realm of forensics and its role in criminal investigation”.(Saferstein,2008)
In cases where a sexual motive may be suspected, and the breasts or buttocks are exposed, it is suggested that swabs from the nipples and surrounding skin, the buttocks, the suprapubic area and the front of the neck are taken. In cases where there are no clear and visible stains, the saliva traces can still be found, if not suction bruises or bitemarks. It is also possible that the accused might have masturbated over the rapped individual rather than having full intercourse. Those compelled to commit fellatio may spit out the seminal fluid so that it is found on the clothing or even on the ground nearby.
In order collect, preserve, and forward the seminally stained clothing, it is necessary that it is not touched by hand. Any stroke of hand should be avoided especially on the stain portion. More so, it has to be picked up with sterile forceps. It is also essential that the seminal stain be dried properly. In case it is not dried properly, the likelihood of an increasing bacterial growth looms large threatening its contamination too. Electric fans are not supposed to be used for drying it.
Once it is properly dried, it should be covered in a fresh blotting paper and packed in a Zip lock poly bag. For that matter, no preservative is needed and it may be transported at environmental temperature.
Following its packing process the process of numbering and getting it sealed comes. In order to preserve it, the samples need be kept separately so that each case sample can be identified and recognized easily. Blood can create problems and it becomes necessary to ensure that no preservative is added. It should rather be frozen. Nowadays, the general consensus is that blood alcohol level becomes unreliable and useless to the investigation process after the use of commercial fluoride/oxalate containers.
Saferstein, Richard(2008) “Criminalistics, An Introduction to Forensic Science, ninth edition”