Body Fluids – Identification and its Medico-legal Significance


Forensic science is the scientific method in helping to solve criminal cases or in a criminal investigation.

Nobody earlier knew that the fluids that run through bodies have individual characteristics, that do not match to the others. Almost after so many years when forensic science came into existence, it is when Sir Alec Jeffrey realized in 1984 that the variations in generic code could be helped as a feature differentiating one individual from another, even one twin from another twin.

The first-ever application on the recently developed science was done after a year when a 15-year-old girl was raped and murdered. The police did not find any suspects but were able to obtain a semen sample. In yet another subsequent year, there was another rape and murder of a 15-year-old girl. Forensic showed that in both the cases the murderer was the same, because of the same blood type.


Because of which DNA databases developed, considering body fluids as very important for criminal investigation. The ability to identify a person even from a drop of blood or semen came into scope on a large scale.

A list of body fluids includes:- blood, semen, saliva, faeces,  sweat, vaginal disposal, nasal secretion, urine, etc.

Considering blood and semen as the most important body fluids found on the scene of crime, there are some sections involving its collection because no person who we have a doubt on would be willingly giving their tests for the same. Saying in other words, would not it be the same as handcuffs being declared unethical for criminals because the court says they are ‘no animal’?

The situation arising at this point where the undertrial prisoners are compelled to give the samples. Where under the new code there is such a power? In fact, section 53 of the Code of Criminal Procedure provides that while making such an examination such forces as is reasonably necessary for that purpose may be used. Therefore, whatever discomfort that may be caused when a sample of blood and semen are taken from an arrested person it is justified by the provisions of section 53 and section 54 of the code of criminal procedure (Ananth Kumar Naik v. The state of Andhra Pradesh).

After coming of forensic science into existence, and two murders where same profile blood and semen was collected, there was a future view that bodily fluids are the best pieces of evidence. These fluids contained within the human body and those which are found on the victim of the crime. The first step for the examination being that they are swabbed, bagged and collected in vials, which are airtight and at low risks of cross-examination.

Before the forensic scientists work with tests of the clues found on the scene of the crime, they commence with the visual examination. They require patience, concentration and a lot of lights, used for objects which are not visible from naked eyes. A month-old bloodstain changes colour by being in contact of the environment and or the base it is on, which requires proper testing, also the objects which are transparent in colour like saliva, semen, which do have a slight colour, can be discoloured or changes colour after a period of time.

It requires varieties of lights for scientists to examine every minute detail. For basics, there are a lot of lights available in the forensic market – lights which makes the body fluids florescent which requires darkness and eye protection. In cases of sexual assaults, merely saying and pointing out at the person who did it is not sufficient. However, a case is not determined by what one believes, but rather by what the investigation shows and can be proved.

The most common body fluids found on the crime scene are blood, semen, saliva, but others such as vaginal secretion, sweat, urine also help us to identify the DNA profiling of an individual. The detection and identification of body fluids at a crime scene are very important aspects of forensic science. Determining whether or not there is a body fluid present and subsequently identifying DNA analysis which is a very crucial step in a wide range of investigation.

Sometimes just knowing the identity of a fluid can be enough to influence the outcome of the case since many body fluid stains are either invisible to the naked eye or similar in appearance to other fluids or substances.


Blood is merely a fluid containing biological and chemical characteristics, which is liquid in nature and contains blood cells and plasma. An average person can survive 1/3rd of the total blood and more than that can lead to death.

The most common body fluid that could be found where the incident has taken place is blood. Bloodstains could be found in patterns, either a pool of blood, blood over the clothes, or such minute stains of blood which are not even visible to naked eyes. Being the most important biological traces and the valuable information it contains, it is considered as the most important forensic tool.

Depending on the force that was used or the way or the thing where the person landed on, the bloodstains take various forms. The bloodstain depends on the surface tension also; if fell from 90 degrees making a spherical shape of the drop, if fell on a carpet, it disrupts the shape and spreads all over which is almost a spherical shape.

The bloodstain pieces of evidence could be collected in the way of either cutting the surface where there is blood if possible, drying and packaging, photography, sketching materials etc. Investigators or analysts soak the bloodstain or collect the dry blood in order to determine human blood and then can check for DNA profiling.

Valuable information can be obtained even from a single drop of blood by analyzing its chemical compounds and its morphological characteristics; telling about what truly happened at the crime scene by investigating and putting some practical application of violent acts and bloodstains.

In SONELAL V STATE OF MP[1], sating from the forensic report that the blood found on the knife which belonged to the accused matched to blood found on the underwear of the deceased. In STATE OF MP V BHARATLAL[2], presence of blood, spermatozoa and vaginal secretion on her vagina slides and petticoat were used as useful evidences.


Semen is the second most common form of material tested for DNA. It is almost certainly the primary evidence in most of the sexual crimes such as rape. It is, in fact, the sperm heads that contain the DNA rather than seminal fluid. Therefore, before DNA analysis is performed, it is advisable to ascertain first whether the material is actually semen and does contain sperm. Testing aspheric semen would clearly be of little value since there would be no sperm present. Semen stained clothing should similarly be examined to confirm the presence of sperm.

Semen may found in liquid form or as dried smears or stains. Or, it may be found in vagina, anus or rectum. Fresh semen is a gel-like fluid, which liquefies on exposure to the atmosphere. A normal ejaculation is about 3.4 ml, containing about thirty million sperms. The dry weight is about seven per cent of the liquid weight. The sperm has a definite morphological structure. Its identification in a stain establishes its seminal nature. The shape and size of human spermatozoon is characteristic. But the morphology alone dose not permit individualization.

Semen of some persons does not contain spermatozoon. It is called aspermic semen. This may be due to some disease or it may be due to vasectomy operation. In such cases, identification of semen from sperm is not possible. However immunological test using anti-semen sere against seminal plasma are increasingly being accepted as a reliable test for aspermic semen.

Chemically, semen is a complex mixture of organic and inorganic compounds. Important constituents of semen, from identification point of view, are proteins including enzymes, blood group factor, choline, fructose, citric acid, uric acid and zinc. The composition varies from individual to individual.

Visual location of semen is a difficult task, because the stains are almost colourless and can be destroyed by washing. Semen strains are found on the victim and the culprit on their garments, at the scene of occurrence and in the vehicle in one is used for the commission of the crime. In JAGAT RAM V STATE OF H.P[3], the prosecutrix was exposed to intercourse since after examination by forensic scientists semen stains were found on her salwar, for example. In SURESH KUMAR VS. STATE OF HIMACHAL PRADESH[4], the court observed that no complete penetration is required even if the penetration is of some extent it is said to be rape; in this case, no semen was found inside the vagina of the victim.


Saliva is a complex biological fluid secreted from acinar glands. Saliva samples can be coupled with forensic in determining the DNA profiling of an individual and forensic evidences. Samples of saliva and mouth swabs in the DNA testing is much easier than blood, since the sample taking is easy, painless, and could be a form of test for children also. No religious complications are also there which are present in blood. It is found to be an emerging forensic tool in cases of drug abuse, bite marks analysis, sex determination etc.

In GOVIND SINGH VS. STATE OF RAJASTHAN [5], a  10- year old girl being raped and murdered, sample of saliva of accused-appellant was a valid piece of evidence. In STATE OF CHHATTISGARH VS. SUNIL AND ORS[6], saliva spit was found at the place of the incident, sent to the forensic science laboratory for examination.


This fluid protects the vagina of the women, a mixture made up of cells, liquids and bacteria. Forensic science plays an important role in identifying the group of semen found contaminated with vaginal secretion, because the victim mainly in such criminal cases is a female, and hence known to us.

Detection and persistence of epithelial cells, lactic acid, mucus, Doderlein’s bacillus, from vaginal secretion stains have been reported. After an incident, epithelial stain remains for 4 and a 1/2 month whereas doderlein’s bacillus stains get completely removed after a month. In KLENDRO TYNHIANG VS. THE STATE OF MEGHALAYA [7], vaginal swabs of the prosecutrix and the salwar she was wearing was sent to the laboratory, the report of the laboratory stated the presence of semen on the vaginal swabs as well as on the salwar. In ANIL KUMAR VS. STATE OF HARYANA[8], the death was caused due to head injuries but further opinioned after sending the samples of vaginal sabs that it was sexual intercourse.


The type of evidences available at the scene of crime is very important, mostly in cases of sexual assaults, where body fluids play an important role in estimating the situation that must have arose at that moment. Collecting the specimen exactly after when the incident has occurred is not always possible, which may lead to falsifying or degradation of the pieces of evidence left or exchanged.

In cases of rape, it abides to the provision that the examination has to be done by the person registered under the state medical council of India, i.e. the registered medical practitioner (RMP), according to sec 27(2) of POCSO ACT, Protection of children from sexual offences Act. For a girl below 18 years of age, the examination has to be compulsorily done by a female RMP, if not available then by any other person if the consent been given by either the victim herself or the guardian. For medico-legal examination of a girl below 18 years of age the consent has to be given by her parents making it compulsory.

  • The victim’s guardian/parents have the right to refuse for the medico-legal examination, but the refusal is not denial for the medical treatment of the survival after sexual violence.
  • The person being medical examined should know the procedure for the test, the nature of the same, and in case of a child, the child’s parents.
  • It includes substances taken from vagina, rectum, removal of clothing, removing the hair of the pubic area etc.
  • The two-finger test should not be conducted and no comments should be made regarding the vagina or the habitual vaginal intercourse.
  • For the purpose of detection of semen, vaginal secretion, blood and for the DNA test of the victim, there are some basic precautions that have to be taken immediately after the incident been reported for the test, like evidences taken from the underclothes of the victim like bra, panties, salwar etc., also making sure the victim undresses on a plain white cloth so the evidences do not get mixed up due to any colorful sheet. The cloth having blood stains need to be dried and all the clothes to be packed inwards keeping a paper in between and has to be sent to the laboratories as soon as possible.
  • In case of the sanitary pad, it is not to be removed from the pants but if removed for examining, the wax needs to be applied at the backside of the sticky side of the pad, so that it does not stick to any paper. This is done for testing the spermatozoa/semen and for identifying the DNA profiling of the accused.
  • The condom used in the assault may be collected for the testing of sperms or vaginal secretion.
  • In case of determining the prints or stains on the body which are not visible through naked eyes, ultraviolet light source could be used for the same. Any sort of bite marks present on the body has to be photographed. Any foreign material, hair available on the body has to be collected separately and to be kept in a catch paper.
  • Nails of the fingers of both the hands to be collected in a white butter paper, for establishing physical contact during the assault.
  • Urine and vaginal wash to be kept in a sterile plastic container for pregnancy test and for determination of sperms.

[1] AIR2009SC760

[2] 2009(3)CGLJ30

[3] 2009CriLJ3271

[4] MANU/HP/3069/2011

[5] MANU/RH/1332/2016

[6] MANU/CG/0155/2016

[7] MANU/MG/0054/2017

[8] MANU/PH/2345/2016


Abhya Soni

Abhya soni

Abhya Soni is third-year law student in Banasthali Vidyapith. She is an aspiring legal practitioner fighting for her dreams. A budding lawyer who’d be honored to be the voice of the victim. To serve is the goal of her life. She is motivated to help improvise the judicial system of India for Indians settled abroad and believes that justice should not be delayed because of geographical boundaries. She has been meticulously working as the legal content lead at ‘LawAdvisor India – Indian divorce lawyers in USA’ for the last 6 months.

One response to “Body Fluids – Identification and its Medico-legal Significance”

  1. Wow that’s really nice the way you portrayed the things in this blog I mean best.


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