Have you watched the Bollywood movie Talwar? It captured the lapse in Investigation which led to miscarriage of justice during trial in Aarushi Talwar murder case. There is one point where blood stained hand print could help trace the culprit, but the Investigating Agency missed out while it got washed away in rain. To avoid such lapses, the authorities have in place the DNA Handling Guidelines in India. In fact, the recent Supreme Court Guidelines on Management of DNA Evidence also lead the way for authorities handling biological evidence. Let us scan through the same to understand how investigation has to be done at a crime scene where biological or DNA evidence has to be dealt with care to reach the culprit.
DNA Handling Guidelines in India
Given below are the guidelines shared by the Central Forensic Science Laboratory (CFSL), Chandigarh. The guidelines have been summarised below. For detailed guidelines and format of evidence submission form, Click Here.
Preliminary Survey
The authorities are required to conduct an overall survey of the crime scene. They may evaluate and establish a path of entry and exit to the scene, and the same should strictly be utilized by authorized personnel. They also need to evaluate boundaries of the initial crime scene. The DNA handling guidelines in India require the Investigating authority to conduct a “walk-through” of the crime scene and document the details. The identification and protection of fragile, perishable evidence is upon the authorities. They must prepare preliminary documentation of the observations and ensure that compromisable evidence is documented, photographed and collected immediately. Identification of origin of the incidence and reconstruction of sequence of events needs to be duly accomplished. The sequence of events should not contradict with the statement of witnesses.
DNA Handling At Crime Scene
- To avoid unwanted access at crime scene (be it curious people or malicious intentions), the Investigating Agency may establish a perimeter using police line tape.
- To prevent contamination of crime scene or evidence, the officer in charge may restrict anyone from entering the premises.
- The Investigating Officer must wear gloves and protective clothing. This has to be done as a matter of caution to reduce the chances of contaminating DNA evidence.
- The Investigating Authorities must keep track of ingress and outgres of people and animals at the crime scene.
- They should maintain the privacy and confidentiality of the crime scene.
- To maintain the integrity of crime scenes, the media and press personnel should also be restricted.
Controlling Contamination of DNA Evidence
Contamination control and preventing cross contamination at the crime scene crucial for maintaining the integrity of evidence. That is why the authorities should limit access to people directly involved in processing. The Investigating authorities should use protective equipment in order to prevent and minimize contamination of crime scene. They should use disposable devices in compliance with DNA Handling Guidelines in India for collecting biological evidence.
DNA Handling Guidelines on Documentation
The Investigating Officer has to maintain documentation of DNA evidence as a permanent record. They need to review preliminary survey of crime scene of crime to determine the kind of documentation needed. It could be photography, video, sketch, measurements, notes, etc. The notes and reports need to be recorded based on facts in a chronological manner without any opinions, analysis or conclusions. A general description of the scene of crime should be given just like how the Investigating Officer sees it while conducting the preliminary survey.
Sketching of Crime Scene
The Investigating Officer has to reduce the crime scene in the form of a sketch. The sketch of the crime scene could be a rough sketch. However, the sketches in heinous crime cases should be scaled, and distance should be measured accurately so that nothing important is left out of the sketch map. The exact position of one or two permanent fixture should be provided to ascertain its distance from major articles, exhibits, marks such as blood stains, track marks of vehicles, etc. The compass point should also be indicated obtaining the north point with the help of a compass. The corner of the sketch should provide the title, case reference, date, time, name and signature of the Investigation Officer.
Photography of Crime Scene
Photography should be used as part of documentation for all physical crime scenes. As per DNA handling guidelines in India, the photographs should capture the dead body (if present) to show locations, injuries and condition. Each and every piece of evidence should be photographed to depict the place where it was found. This will help connecting the dots of evidence with the victim. Evidentiary photographs should be taken from straight above eliminating potential distance distortions. Even the blood pattern should be photographed from different angles along with the scale. The Investigating Officer must identify the type of weapon of offence from the pattern of blood stain.
Guidelines for Searching Crime Scene
- The Investigating Officer must adopt an orderly approach to access the crime scene so that any material evidence is not left out.
- Any one of the following crime scene search pattern may be adopted
- Line or Strip Method: The Investigating Officer may walk a path from one end of the crime scene to the other side of the room/area and then return in the direction from where they first started. This method is useful for large and outdoor scenes of crime.
- Grid method: This one suits best for large crime scenes such as fields. It is basically a double line search where the searcher moves from one end of the area to the other.
- Wheel or Ray method: This one proves best for small and circular crime scenes. The searchers gather at the center and proceed outward along the radii.
- Spiral method: The method is best used where there are no physical barriers (eg., outdoor scenes). The searcher examines the area for evidence in an ever-widening circle, starting from the center or core of the crime scene, moving in an outward direction.
- Zone method: This one proves effective in houses or buildings. The area is divided into four quadrants / squares and then examined using previously described methods.
Preservation, Packaging and Forwarding of Biological Evidence
- Identify and secure evidence in a container right at the crime scene.
- Once collected, avoid excessive handling of DNA evidence.
- Paper bags / paper sheets / paper envelopes are recommended to prevent deterioration of a biological sample (if it is not completely dry when packed).
- The use of any printed paper is prohibited since the ink may contaminate the exhibits.
- Each article should be separately packed and labeled.
- Packing more than one item together is prohibited.
- Each exhibit should be labeled with FIR no. and date, under section, name of IO, police station, district, state. It should be duly signed and sealed by the IO.
- The exhibit labels should be numbered consecutively and should bear the signature of the Forwarding Officer.
- Labeling should be done on the cover instead of evidence.
- All the packets belonging to one case should be enclosed in ONE box or an outer covering.
- Hair samples should be collected with the help of tweezers and placed in small paper bags.
- Dried blood may be either scrapped on a paper, or fingerprint tape / cello tape may be used to lift the dried blood stains. This can also be collected by using surface swab / gauze / filter paper / FTA card moistened with distilled water.
- For wet blood stains, they may use the aforementioned method by cotton swab and put in a paper bag after air drying the same.
- If the evidence is to be collected from a pool of blood, then dropper or syringes may be used to lift the sample in EDTA (Ethylendiamine tetra acetic acid) vial and simultaneously be lifted on sterile tipped foam surface swabs.
- For health and safety concerns, it is recommended not to touch the biological evidence with bare hands but only with gloves.
- DNA Handling Guidelines in India strictly restrict Wet or moist items in plastic or paper containers for less than two hours. The articles must be air dried before final packaging. Drying stain material by heating or placing the article in bright sunlight is prohibited.
Maintaining Chain of Custody of DNA Evidence
Chain of custody is the process used for maintaining and documenting the chronological history of the evidence. The Chain of Custody document should be maintained to include the name or initials of the individual collecting the evidence, each person or entity having its subsequent custody, dated the items were collected or transferred, agency and case number, victim’s or suspect’s name and the brief description of the item.
Crime Scene Investigation Kit
The Investigating authority is required to handle the evidence with care. They should not touch biological evidence with hand and need to document each and every detail of the crime scene. Therefore, they need some equipment to conduct the survey:
- A high resolution digital camera
- Disposable Gown, Cap, Shoe, Gloves, Mask, Goggles, hand-towels. Biohazard polythene bag for biological waste.
- Sterile gauze, Filter paper and dessicant
- Alcohol swabs and tissue, hand sanitizer
- Evidence marking letter, alphabets and direction indicators
- Hand torch and magnifier lens
- Surgical blades, forceps, scissor, dropper and syringe
- Sterile water, saline and phosphate buffer
- EDTA vials and FTA cards
- Surface swabs, Cotton swabs and plastic container
- Evidence collecting envelopes and cardboards
Instructions for Using Crime Scene Investigation Kit
- Clean and sanitize hands before touching the kit
- Wear barrier clothings such as gloves, mask, gown, shoes, cap.
- Try to avoid sneeze and cough on evidence items
- Use UV-lighter to spot and identify body fluids
- Only use swabs / FTA card / gauze piece to collect semi dry / liquid body fluids
- Dry / old stain should be moistened with PBS buffer and left for 5 min
- Collect the stain with the help of FTA card or tipped foam surface swab
- Air dry the stain before packaging
- Refer procedure for collection of biological evidences
- Everything should be done in compliance with the DNA handling guidelines in India.
Documentation for Submission to DNA Division
- Letter from SSP addressed to the Forensic Science Laboratory so concerned.
- Brief history of case (5-10 lines).
- Details of each parcel along with impression of seals and number of seals affixed on the parcels.
- Type of examination required.
- Enclosures with SSP letter.
- Copy of FIR in English or Hindi.
- Vernacular report MLR/PMR of victim issued by the doctor.
- MLR of accused issued by the doctor.
- Autopsy submission form (if applicable).
- Clearly visible and attested sample seals on piece of cloth corresponding to each parcel.
- Blood authentication forms of victim and accused(s) along with attested photograph duly filled by doctor
- Sexual assault form duly filled by doctor along with attested photograph.
- Evidence submission form duly filled by SSP
- Chain of Custody form duly filled by investigating officer
- Aborted Foetus Identification Sheet duly filled by doctor
- Copy of Road Certificate.
- Evidence sample of victim
- For DNA examination, evidence samples such as vaginal swabs, slide of vaginal smear, undergarments along with reference blood samples of victim in EDTA vial/ Gauze / FTA card.
- Evidence sample of accused
- Blood samples of accused(s) in EDTA vials/ Gauze/ FTA card and other swabs such as penile swab if taken by doctor during medical examination.
All liquid blood samples of victims and accused should be kept in EDTA vials with details, signed by a doctor on each EDTA vial. Separate packaging is also required. Only liquid blood in EDTA vials should be transported in a dry ice storage box for maintaining the temperature at least 4°C until its submission in the laboratory. Aborted foetus should be preserved and stored in cold condition without adding any chemical preservatives. Bone samples should be dry and clean, since no chemical preservative is required for storage. Standard reference blood samples of both accused and victim are required in sexual assault cases. In Paternity/Criminal Paternity case, standard reference blood samples of both alleged parents are required.
Supreme Court Guidelines on Management of DNA Evidence
The Supreme Court on July 15, 2025 decided the case of acquittal in Devakar v. State of Tamil Nadu. As the case required and for the importance it held for other similar cases, the Apex Court issued some DNA handling guidelines in India. Those guidelines need to be followed by those involved in handling DNA samples.
Kattavellai Devakar v. State of Tamil Nadu Case 2025
Given below are the Supreme Court Guidelines on management of DNA evidence:
- The DNA samples should be collected after due care and compliance with DNA handling guidelines in India.
- The appropriate packaging should highlight the following:
- FIR number and date;
- Section and the statute involved therein;
- details of I.O., Police station; and
- requisite serial number shall be duly documented.
- The said document of packaging should contain the designation and signatures of the following:
- medical professional present;
- investigating officer; and
- independent witnesses
- The DNA handling guidelines by Supreme Court clarify that absence of independence witnesses is not to be taken as compromising the DNA samples so collected for the purpose of evidence.
- However, the efforts made for including such independent witnesses and such inability needs to be noted on record.
- The responsibility of transporting DNA evidence to the police station or hospital so concerned lies with the Investigating Officer. Further, such IO should make sure the DNA evidence reaches the forensic science laboratory with dispatch within 48 hours since collection time. In case of extreme circumstances making it impossible to make it happen within 48 hours, the reasons be duly recorded in the case diary.
- Efforts should be made for preserving the samples as per DNA Handling Guidelines in India, depending upon the nature of sample taken.
- During pendency of trial, appeal, etc. the DNA handling guidelines restrict opening, alteration or reseal of the samples without express authorisation. The Trial Court may allow so following the statement of a duly qualified and experienced medical professional. Even if allowed, the sanctity of the DNA evidence should remain unaffected. Throughout, the Court has to assure if such a step is necessary for a fair trial or investigation.
- The authorities so involved need to maintain a Chain of Custody Register from the point of DNA sample collection till the conviction/acquittal. The Register for Chain of Custody of DNA evidence has to reflect each and every movement along with counter sign at each end with reasons. The said register is to be appended as part of Trial Court Record (added as appendix and assigned a number). Failure to maintain Chain of Custody Register requires explanation by the IO for lapse.
Inference
Based on the DNA handling guidelines in India and the Supreme Court guidelines on management of DNA evidence, a lot of care is required on part of everyone involved. It is crucial because DNA stands a person out of the crowd. Every person has a different DNA and identification goes exact by more than 99% accuracy. But if DNA evidence is mishandled, the very chance of grabbing the culprit’s collar is lost. That is why, due compliance with the DNA Handling Guidelines by the Investigating Authorities is important. That is an ideal scenario.
What holds on the ground is that crime scenes are not as secure. Investigating authorities, that is police, lack the required equipment. In fact, they mostly lack the requisite training to deal with delicate evidence like blood, hair strands, semen, etc. Therefore, a lot of loopholes are there for the perpetrator to flee conviction in criminal trials, which could otherwise be curbed by biological evidence caught at the crime scene.
