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How should evidence be handled?

Jagadeesh Narayanareddy, biological evidence, collection, preservation, packaging and storage of evidence, police
For collecting evidence, also informed consent is a must. This DFSS guidelines also very clearly mandate if there is no consent than an informed refusal has to be documented. All this happens in a survivor examination. In deceased examination, so based on the scientific basis, you collect the evidence. And the DFSS guidelines towards the end gives out the forms. So how to send for an aborted fetuses? How do you send in a medico-legal autopsy, the specimens in a sexual violence case?
The DFSS guidelines also ask us to look for collecting the biological specimens in the sexual assault DNA evidence collection kit. It lists out the elements which are required to be part of the DNA evidence collection kit. Disposable and sterile devices like hand gloves has to be used whenever you are collecting the evidence to avoid contamination. Each exhibit or evidence has to be collected in a separate paper envelope and sealed properly, so that there’s no cross contamination and labeled properly so that they are properly identified. Collecting the evidence is again based on the history. If somebody says vagina being penetrated, vaginal swab is taken. Somebody puts out anus being penetrated, then anal swab is collected.
So there is a scientific basis for collecting. Somebody says a month back was the sexual offense and today there’s no point in collecting anal swab or oral swab. Because definitely post assault there would have been urination, defecation or washing of the mouth, which all would have removed the trace evidence, whatever is present. Both the DFSS guidelines as well as the Ministry of Health and Family Welfare guidelines, give a detailed procedure of how to pick the evidence. Annexure 4 of the Ministry of Health and Family Welfare guidelines very clearly point out in which scenario, which type of swab has to be collected, what is the purpose and what points have to be looked for.
To give you an example, in a peno-vaginal sexual intercourse, there are two types of swabs you collect. One from the vagina and the other from the body surface. You pick up the vaginal swab, the purpose being, there could be possibility of detection of semen or spermatozoa. There could be possibility of detection of lubricant, if it is being used and DNA could be extracted from all these things. Another care should be taken whenever they are making slides out of these swabs taken. All the swabs and slides have to be air dried in shade. Never put under sunlight or never use a hair dryer or heat blowing thing because the proteins get denatured and that may destruct the evidence.
These swabs and slides should be properly packed, labeled, sealed and then only transferred to the next in the chain of custody. All stakeholders to also understand the process of preservation, packaging and labelling of samples. Because if a appropriate preservative is not used before the swab or before the evidence reaches the laboratory for further analysis, that interferes with the analysis and estimation or quantification or detection. So normally we use sodium fluoride for any sort of detection of any chemical from the blood. EDTA for picking up DNA and plain vacutainers are being used for drug assay. So all these should be packed, sealed and labeled.
So immediate transfer, if it gets delayed, then there should be adequate refrigeration of these samples at four degrees centigrade or an icebox. Ideal would be an immediate transfer. But in DNA evidence, if you are not able to do it, then deep preservation is something which is required, which may not be available in all the scenarios. If you look at the DFSS guidelines, it insists on minus 20 degrees centigrade, but minus 20 degrees centigrade refrigeration may not be available across all the hospitals. So this is something which we have to keep in mind.
The chain of custody is something, if it is hampered, would lose its value in a criminal trial. So there should be clear documentation of the movement of the sample from whom it moved to who is the one who is receiving that. It should always be in the custody of one authorized handler to the another. And there should be a proper signature and the identity of the person who is handing over, as well as the person who is receiving that. In the interim, it should always be stored in a lock and key. It could be the refrigerators, if it has to be stored at four degrees centigrade or in the almirahs.
So there are certain states, particularly Delhi, way back in 2008 itself, the Delhi High Court had pointed out, let these samples be in the hospital, which would have a better facility than the police stations till it reaches the forensic science lab. So there should be restricted access to only authorised persons to handle this evidence. And as far as possible, there should be minimum handlers who are known, with known identity only handling these specimens.

In this lesson, Dr Narayanareddy explains the manner of collection, packaging and preservation of evidence collected during medical examination.

After watching this video, think about the discussion on the movement and handling of evidence in your jurisdiction. Some aspects for you to reflect on:

  • Are there any guidelines for police or crime scene units for collection of evidence?
  • Do the police have facilities to ensure proper packaging and storage of evidence?
  • What are the legal consequences for the appreciation of evidence that may not be properly packaged, stored or handled?
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Decoding Forensics for Legal Professionals

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