Presence of semen in sexual violence

Does absence of sperm or semen disprove rape? The answer would be no. Semen is absent in non penetrative sexual offenses. Even if it’s a penile penetration, it’s not necessary that in every case there should be evidence of semen. The act could be without ejaculation. So if the act is without ejaculation, then there is no semen. Ejaculation may occur outside the body or outside the orifices. So if it’s outside the orifices, on the surface of the body and if you don’t pick that, then again, there’s no evidence. If it is outside the body at the scene and that is not picked up. Then again, you don’t have.

Or it could be a case of use of condom and that condom is not recovered. Then again, you don’t have that trace evidence of semen, even though it’s a penile penetration. And again, if the medical examination gets delayed. There are many post assault activities which happen, so that may also remove this semen from the these orifices like washing, douching. There’s another issue which we have to understand, semen and spermatozoa. Spermatozoa is a constituent of semen. So it’s not necessary in every case of semen you need to find spermatozoa. So all vasectomised individuals will not have spermatozoa, after that minimal three month period. And whenever there is a disease of Vas diferens, also, the spermatozoa would not be there.

Again in Azoospermia and Necrospermia conditions there, variation in the content of the spermatozoa. So it’s not necessary in every case of semen stain, you pick up spermatozoa. What are the tests to detect this semen? There are two types of tests which the normal forensic science laboratory does. The presumptive test would be picking up like barberio test florence test, acid phosphatase test. Acid phosphatase is present in many body fluids, including that of semen. P 30 assay. So if you pick that, they are only of presumptive value. Confirmatory tests would be that of detecting semenogelin or immunological assay. But the ideal confirmative test would be for detection of spermatozoa.

So if I pick up spermatozoa, so that spermatozoa would present only in the semen. So that would prove 100 percent that it was semen. But the absence of spermatozoa would not rule out that it is not semen. What factors affect the detection of sperm or semen? So in case of survivors, it all depends on when we are examining. If the examination is delayed, so then the chances of you picking up that spermatozoa would go on decreasing. Even the semen also would decrease as the time delay. Whenever there are post assault activities, like washing, douching, bathing, even urination and defecation, also would remove some part of the trace evidence of semen in spermatozoa from those orifices.

So whenever the seminal stain is present on the outdoor surfaces, like it’s on the cot or it’s on the surface floor or it’s on outdoors. So the chances of you detecting that goes down with the delay in the examination. If we are able to pick the entire sperm morphology and the sperm is motile, so then you could conclude that it is within 12 to 24 hours of the sexual act. If I am not picking the motility of the spermatozoa, but I am only picking up that the sperm morphology is intact, the head, neck, tail. So then we can conclude that it is between 24 to 48 hours.

But after 48 hours or so, the only possibility would be the detection of the sperm head. In case of deceased victims, what factors would affecting picking up this spermatozoa? Again, the time of examination. Whether the dead body was recovered from a moving water. So, again, whether the water was possible to enter into these orifices. Again, that depends on the clothing. Whether there are clothing on the body, if the clothing are present on the body and that covers the orifices, still, these stains may be intact, even though it’s a moving water. But if there are no clothing covering those orifices and then there is a moving water, there is a possibility that some of the stains may get washed away.

Another aspect which has to be kept in mind, effect of decomposition. So decomposition would destruct all the organic tissues in the body to convert into inorganic elements as the time progresses with decomposition. The chemical part of it, you may still pick in a decomposed body. But again, there are many false positives and false negatives for picking up those chemical part of the semen.