DNA Fingerprinting

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Delhi Police recovered bones from the Mehrauli forest area in connection with the Shraddha Walkar murder investigation using DNA Fingerprinting.

Origin of DNA Fingerprinting

DNA fingerprinting was first developed in 1984 by Alec Jeffreys in the UK.
- No two people could have the same DNA sequence.
UK achieved the world’s first conviction based on DNA evidence in a case of rape and murder.

How is DNA fingerprinting done?

Each person’s DNA except for identical twins is unique.
By analysing selected DNA sequences (called loci), a crime laboratory can develop a profile to be used in identifying a suspect.
DNA can be extracted from many sources: such as hair, bone, teeth, saliva, and blood.
- Samples may even be extracted from used clothes, linen, combs, or other frequently used items.
There is DNA in most cells in the human body: even a minuscule amount of bodily fluid or tissue can yield useful information.
Advanced DNA fingerprinting can make separate prints of various individuals even from a sample mixture found at the crime scene this is of help during gang rape investigations as each perpetrator can be individually identified.

DNA evidence is used to solve crimes in two ways:

If a suspect is known that person’s DNA sample can be compared to biological evidence found at a crime scene to establish whether the suspect was at the crime scene or whether they committed the crime.
If a suspect is not known, biological evidence from the crime scene can be analysed and compared to offender profiles in existing DNA databases to assist in identifying a suspect.

DNA fingerprinting in India

By 1988, Lalji Singh, who had been in the UK from 1974 to 1987 on a Commonwealth Fellowship, developed DNA fingerprinting for crime investigations at the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad.
- Lalji Singh, who passed away in 2017, is known as the father of DNA fingerprinting in India.
In 1989, DNA fingerprinting was first used in a case by the Kerala Police.
By the early 1990s, the technology had begun to be used for establishing paternity, and to link criminals and identify victims in sensational crimes.
From the 2000s onwards: the technology became a staple in rape cases where vaginal swab samples were matched with semen samples from suspects.

Challenges with DNA fingerprinting in India

Use of proper equipment is needed: It is vital to ensure that the DNA of the investigators does not get mixed with that of the victims or the suspects. Thus, picking up samples from a crime scene with sterile tools and storing samples in a proper manner are crucial for the evidence to stand a judicial test.
Lack of expertise: While central agencies such as CBI have the expertise to ensure that crime scenes are protected and correct procedure is followed, state police forces are inadequately trained or fully equipped.
The capacity for DNA fingerprinting in the country itself is lacking. DNA fingerprinting is available only at a few places Maharashtra, West Bengal, Delhi, Hyderabad and Chandigarh.
- Advanced practices in the technology are limited to the Centre For DNA Fingerprinting and Diagnostics (CDFD) in Hyderabad.

Some famous investigations where DNA fingerprinting was used

Shiney Ahuja rape case: Despite his maid’s statement denying that she was raped, in March 2011, Bollywood actor Shiney Ahuja was convicted and sentenced to seven years of rigorous imprisonment. The fast-track court delivering the verdict relied heavily on DNA evidence, in which semen samples from the vaginal swab of the victim matched with the samples obtained from the accused.
Establishing the identity of suicide bomber who killed Rajiv Gandhi: It was DNA evidence that established the identity of Thenmozhi Rajaratnam who had detonated the bomb that killed ex-PM Rajiv Gandhi and 15 others in 1991. Evidence was gathered from charred flesh and bones found at the site of the explosion.
Sheena Bora murder case: DNA from some charred bones were discovered in a forest in Raigad, Maharashtra, in August 2015, and matched with the DNA of media entrepreneur Indrani Mukherjea. Until then, she had maintained that her daughter Sheena Bora was away in the USA.

Source: IE

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