Detection of Semen Stains
Need for Court’s vigil
When a semen spot is traced on the Spot of Occurrence then the investigation has to establish twofold results from this spot.
- That this is a Human Semen, and
- That this contains a DNA information which is precisely similar to that of the accused.
The first part of the result is obtained from a Serological Examination while the second part is confirmed through the DNA Fingerprinting.
Serological Examination refers to a set of experiments/tests conducted on spots of Body-Fluids available on the Spot of Occurrence.
In India, generally the Trial Court in the state of Delhi use such information of Serological Examination and DNA Fingerprinting more than these are used in any other parts of India. So, in a general parlance, the Delhi Courts are the fore runners in the use of updated information and technologies in this field of science of Body-Fluids.
The Delhi High Court while deciding State of NCT V. Khursheed had given directions for lodging an FIR against two senior scientific officers of FSL Rohini. It does not mean that the malpractices are no more in that area of FSL. Rather it confirms the need for the Courts to be more vigilant in accepting the serological and other Forensic Reports.
A Judge is said to be an expert of experts. And he really is because of the office he occupies. He gives the ultimate dictum and the opinion of an expert under Section 293 CrPC or otherwise gets merged in the decision of the Judge. Therefore, the Judge in a Court also needs to be a Real Expert Of Experts, more than a mere phonetic expression.
What the semen is
Seminal fluid is a complex mixture of secretions from at least four male urogenital glands. The seminal vesicle gland contributes approximately 60% to this mixture, the prostate gland contributes approximately 30%, and the combined contribution of the epididymis and bulbourethral glands account for the remaining 10%[1].
An average male ejaculate measures around 3.5 ml. Each ml can contain between 10 and 50 million sperm cells. This number can vary with the age of the male, and can be negatively impacted by medical conditions, genetic background, diet, and other habits such as smoking and illicit drug use[2].
After ejaculation, the latter part of the ejaculated semen coagulates immediately[3], forming globules[4], while the earlier part of the ejaculate typically does not[5]. After a period typically ranging from 15 to 30 minutes, prostate-specific antigen present in the semen causes the decoagulation of the seminal coagulum[6]. It is postulated that the initial clotting helps keep the semen in the vagina[7], while liquefaction frees the sperm to make their journey to the ova[8].
A 2005 review found that the average reported viscosity of human semen[9] in the literature was 3–7 cP[10].
Coming back to the topic:
If a spot is suggestive of being a semen spot then it has to withstand a three layered test in a Serological Examination. The first among them is a variable light test.
1. Variable Light Test
Some experts also call it Visual And Alternate Light Test. If the area to be examined and analyzed for semen is larger than an individual swab, forensic scientists resort to visual identification first. Dried semen stains are often off-white to faint yellow in colour.
Semen can also be visualized using blue light, ultraviolet light (also known as Wood’s Lamp), or a modern light source such as CrimeScope that is properly configured with optimum wavelength filters.
In many practices, a Wood’s lamp with wavelengths from 280 to 360 Nano-meters (nm) is used as the light source to identify potential DNA evidence. But a ResearchGate study shows that The Wood’s lamp (WL) has been used in sexual assault evaluations. Recent data have shown that semen does not fluoresce with a WL and that physicians are unable to differentiate semen from other common medicaments using a WL[11].
Related to this problem is clothes or materials that have been treated with, or washed with detergents containing optical brighteners. These brighteners are designed to fluoresce under UV-Violet (415 nm) excitation. This may limit the use of UV or Black Lights as these devices cause the background to fluoresce as well. To eliminate the fluorescence of the cleansers or detergents, use a Forensic Light Source tuned above 440 nm[12].
But the problem is that not only the semen spot fluoresce in UV Light, detergents and whiteners also fluoresce along with the semen spots. The Courts are generally not inclined to accept this kind of evidence because there are chances of false positive results.
2. Presumptive Tests
Presumptive tests are those which have a credibility of low level. They indicate the possibility of existence of a particular fact. But still presumptive tests may fail in 100% reliability.
a. Acid Phosphatase test:
The male prostate gland produces and secrets into semen a high amount of the enzyme acid phosphatase (AP). Using a standard chemical reaction, a forensic laboratory can analyze a given stain for the presence of this enzyme. In the presence of Alpha-Naphthyl acid phosphate and Brentamine Fast Blue, AP will produce a dark purple color in less than a minute (test is also known as the Brentamine spot test). The shade of this purple color will depend on the activity of the enzyme, which can be negatively impacted by the age of the stain and the storage conditions. The test for AP remains highly presumptive due to the fact that vaginal secretions and other bodily fluids contain detectable levels of this enzyme.
The acid phosphatase test has potential interferences which include male urine, saliva, and feces which, however, contain the enzyme acid phosphatase at lower levels than semen[13]. It has also been suggested that plants, fungi, and bacteria may contain enzymes similar to those of seminal acid phosphatase that produce a reaction to the AP test[14] . For example, teas that are made from Camellia Sinensis which display a colorimetric reaction when tested using the acid phosphatase-fast blue test[15].
3. Confirmatory Tests
Confirmatory tests for semen is called the Christmas tree stain and another one is the p30/PSA RSID kit.
a. Christmas Tree Test
For the Christmas Tree Stain, the sample is extracted with sterile water in order to make a wet mount on a microscope slide. The sample is then heat-fixed to the slide and stained with nuclear fast red for 15 minutes, then rinsed with deionized water[16]. Next, a green stain is applied for 10 seconds, then rinsed with ethanol. The slide is placed under a compound light microscope for sperm observation. If sperm are present, the heads will stain red and the mid-piece and tail stain green[17]. However, not all males release sperm in their semen. If a male is aspermic or oligospermic, they either have no sperm or a low sperm count. Vasectomized males will not release sperm either[18].
When sperm cells are not present, a second confirmatory test, the p30/PSA test, is performed[19].
Fabrication POSSIBILITY
See this video of 41 Sec.
https://www.youtube.com/watch?v=fCJ8TIeKH0w
Watch this video for 41 sec. The person wets the bud in water and then on the suspected stain. In the next stage, rubbing bud on stain he rubs it on test kit and gets the result.
Now change the last step. After rubbing bud on stain he does not take to the test kit but dips is back in the glass of water.
The whole glass of water will now give positive test for the semen. This is the secret how they are doing it in India. This much semen can be taken from any where related to the accused – his underwear or even after his arrest.
[1] https://ncforensics.wordpress.com/2011/10/19/forensic-tests-for-semen-what-you-should-know/
[2] Ibid
[3] Gallup, Gordon G; Burch, Rebecca L (2004). “[Semen Displacement as a Sperm Competition Strategy in Humans]”. Evolutionary Psychology. 2 (5): 12–23. doi:10.1177/147470490400200105
[4] Dean, Dr. John. “Semen and sperm quality”. Retrieved December 7, 2006.
[5] Baker, R (1993). “Human sperm competition: Ejaculate adjustment by males and the function of masturbation”. Animal Behaviour. 46 (5): 861. doi:10.1006/anbe.1993.1271. S2CID 53201940.
[6] Balk, S. P.; Ko, YJ; Bubley, GJ (2003). “Biology of Prostate-Specific Antigen”. Journal of Clinical Oncology. 21 (2): 383–91. doi:10.1200/JCO.2003.02.083. PMID 12525533.
[7] Gallup, Gordon G; Burch, Rebecca L (2004). “[Semen Displacement as a Sperm Competition Strategy in Humans]”. Evolutionary Psychology. 2 (5): 12–23. doi:10.1177/147470490400200105.
[8] Ibid.
[9] Owen, D. H.; Katz, DF (2005). “A Review of the Physical and Chemical Properties of Human Semen and the Formulation of a Semen Simulant”. Journal of Andrology. 26 (4): 459–69. doi:10.2164/jandrol.04104. PMID 15955884.
[10] CENTIPOISE: a centimeter-gram-second unit of viscosity, equal to 1/100 (0.01) poise. Abbreviations: cP, cp
[11] https://www.researchgate.net/publication/11097345_An_Alternate_Light_Source_to_Detect_Semen
[12] https://spexforensics.com/applications/body-fluids
[13] S. Kind, Journal of Criminal Law and Criminology, 1957, 47, 597-600
[14] Anon, Metropolitan Police Forensic Science Laboratory United Kingdom, Biology Methods Manual, United Kingdom, 1978.
[15] M. Vennemann, G. Scott, L. Curran, F. Bittner and S. Tobe, Forensic Science, Medicine, and Pathology, 2014, 10, 69-75.
[16] Gaensslen, R.E. (August 1983). “Sourcebook in Forensic Serology, Immunology, and Biochemistry” (PDF). U.S. Department of Justice.
[17] Ibid.
[18] Butler, John (2005). Forensic DNA Typing. USA: Academic Press. pp. 39–42. ISBN 9781493300204.
[19] “Forensic Resources”. www.ncids.com. Retrieved 2018-10-25
