In 1983, police found a 15-year-old Lynda Mann raped and strangled outside Leicester, a small village in the UK. Detective Baker after three years of meticulous but fruitless investigation is still clueless. In 1986, he meets Alec Jeffreys a genetics professor at the nearby University of Leicester who has developed a remarkable technique to read DNA which he has recently put to use in proving the parentage of a boy in an immigration case. Shortly after, police discover a 15-year-old Dawn Ashworth's strangled body. The police find a suspect Richard Buckland who confesses to Ashworth's murder. When Jeffrey's analyses the DNA samples recovered from Mann and Ashworth's murder scene, it does not match with the DNA of Buckland. Meanwhile, in the village of Leicester, there's a real sense of fear of having a murderer in their midst. The scientific validity of newly developed DNA technique is under a cloud.
Despite all this, detective Baker meets Jeffreys, and decides on the world's first DNA manhunt, which means testing the blood of every man in the area aged between 18 and 34, to find the killer. Despite the massive manhunt, no match is forthcoming. It perplexes the police. At which time a local bakery employee comes forward and discloses his colleague Pitchfork's deception of having coerced his coworker Ian Kelly to stand in for him when providing a blood sample and of him having used a forged passport to impersonate Pitchfork. When the police test Pitchfork's DNA it matches that of the murderer confirming his presence at both the crime scenes. Police arrest Pitchfork, who pleads guilty in both the murders.
This was the first use of DNA fingerprinting in a criminal investigation. The science-fiction future, in which police can swiftly identify rapists, and murderers from the DNA samples left behind by the criminals had arrived in 1987. Since then, DNA fingerprinting has been a useful tool in law enforcement both in securing correct convictions and in exonerating the innocent. Originally known as "DNA fingerprinting," this analysis is now being called "DNA profiling" or "DNA testing" to distinguish it from traditional skin fingerprinting. DNA fingerprinting, unlike other forensic evidence, is easy to collect and has enhanced accurate analysis by a manifold. Just as every coin has two sides, the DNA profiling technology too, has a darker and gloomier side, the misuse of which can cause huge damage to the individual and to the society. Many fear that DNA profiling could lead to loss of privacy, as DNA would reveal their genetic makeup, their susceptibility to diseases and their tendencies. Besides, the in-adeptness of scientific assistants in the police departments at collecting DNA samples, could cause contamination of samples resulting in false positives.
Although 99.9% of human DNA sequences are the same in every person, Our unique DNA, 0.1% of 3 billion, amounts to 3 million base pairs. That's more than enough to provide a profile that accurately identifies a person. Blood relatives have more similar DNA. If the DNA profile from a piece of evidence is similar but not identical to that of a suspect, officials may investigate blood relatives of the suspect. DNA profiling uses repetitive sequences that are highly inconstant, called variable number tandem repeats (VNTRs), in particular short tandem repeats (STRs), also known as micro satellites. VNTR loci are similar between closely related individuals but are so variable that unrelated individuals are unlikely to have the same VNTRs.
The DNA technology has both civil and criminal uses in today's society. Aside from extensive use in criminal cases it is also being used in identification of DVIs (Disaster Victim Identification), and determination of Kinship and establishing biological parentage. In the medical field it is being used in research to detect genetic defects and prevent its transmission to the offspring and to cure genetic diseases such as Cancer, Diabetes and Alzheimer's disease. It is also being used to match the tissues of the donor and recipient in cases of organ donation.
DNA sequences today are also being used to identify the physical features of the accused such as eye, hair and skin colour from focusing on the genes related to physical appearance. By looking at six pieces of DNA it would be possible to say whether the accused has black hair or brown hair or blue eyes.
Efforts are also being made by scientists to determine the age of the suspect and the tissue from which the sample came by detecting methylation differences in different tissues. Some regions in the DNA undergo gradual changes in the level of methylation;This forensic experts detect by subjecting DNA to PCR followed by DNA sequencing to detect methylation differences.
Today, it's possible for police to do a rapid analysis of DNA even in the police stations. For years, when police wanted to find out whether a suspect's DNA matched with crime-scene DNA, they sent a sample to a forensic lab, then waited a month or more for results.But in early 2017, the police station at Bensalem, in the USA became the first in the country to install a Rapid DNA machine, which provides results in 90 minutes, and which police can operate themselves. Ande is one company that makes a rapid DNA system, also called Ande. Rapid DNA systems like Ande,Nucleix and others perform the same purification, amplification, separation, and detection steps that laboratories do. At the end of the process, about 90 minutes, the system automatically interprets the data to determine a profile, which they used to query the local DNA database. Congress enacted the Rapid DNA Act of 2017 in the USA, which allows DNA profiles generated outside accredited labs to search a database called CODIS. This law allows police to do arrestee testing in states where it is in force, which is to take cheek swabs at the time of arresting a person. A cheek swab generates a DNA profile in 90 to 100 minutes. The next generation DNA analysis systems which are being developed are not only faster but can run many samples simultaneously.
DNA profiling has helped many innocents from being victimised and has even exonerated several convicted people. In 1989, Chicago man Gary Dotson was the first person where a court overturned his conviction using DNA evidence. In Madhya Pradesh, a physically challenged girl gave birth to a girl and the suspicion of having raped the girl fell on the girl's father. The DNA of the dead child, however, did not match with the DNA of the alleged father saving him from being guilty. In 2002, the Court used DNA testing to exonerate Douglas Echols, of being wrongly convicted in a 1986 rape case. The Innocence Project at New York's Benjamin N. Cardozo School of Law in the USA aims to exonerate prisoners wrongfully convicted of crimes. The project uses DNA profiling evidence to support the re-evaluation of criminal cases. Since 1992, the Innocence Project and others have used DNA evidence to exonerate over 300 prisoners, including eighteen on death sentence, of whom one was only five days from execution.
DNA profiling continues to help settle many paternity suits. A person named Rohit Shekhar Tiwari filed a paternity suit against three times Chief Minister of the state of Uttar Pradesh, Shri Narayan Dutt Tiwari. The Delhi High Court ordered a DNA mapping test that confirmed his fatherhood. Not refuting the science behind it, Mr. Tiwari finally accepted Rohit as his son and married his mother Ujjwala Tiwari. In 2016 Anthea Ring, abandoned by her mother as a baby, could use a DNA sample and DNA matching database to discover her deceased mother's identity and roots in County Mayo, Ireland.
DNA profiling also helps in providing secondary evidence. Police suspected Uttar Pradesh Minister Amarmani Tripathi of murdering Madhumita Shukla. The DNA profile of Madhumita Shukla and the unborn foetus of the deceased matched with that of the suspect, establishing the motive for the commission of the murder. In 1992, police used a Palo Verde tree DNA to convict Mark Alan Bogan of murder. DNA from seed pods of a tree at the crime scene matched with that of seed pods found in Bogan's truck. This is the first instance of admitting a plant DNA in a criminal case.
We can also use DNA fingerprinting to identify unidentified dead bodies. Police could fix the unidentified body found in the forest area to be that of Sheena Bora when the thigh bones of the decomposed body sent for DNA analysis matched with the blood samples of Indrani Mukherjee the mother of the deceased and her brother Mikhail.
DNA tests can sometimes be inaccurate, resulting in conviction of the innocent. In, Arushi Talwar case the vaginal swabs could not prove whether it were a sexual assault or if she had had a consensual sexual intercourse. In 1992, John Schneeberger raped one of his sedated patients and left semen on her panties. When the police drew Schnee berger's blood and compared its DNA against the crime scene semen DNA on three occasions, it did not match. It turned out that he had fooled the police initially by surgically inserting a Penrose drain into his arm and filling it with the blood of another person. More serious doubts continue to be raised about the use of DNA evidence by law enforcement. In August 2009, Israeli researchers showed that it is possible to create false evidence by synthesising a DNA molecule in the lab. The scientists could fabricate saliva and blood samples of a person similar to that of a suspect. They also showed that it was possible to get a DNA sequence from a database and create one without getting a DNA sample of the person whose DNA was being duplicated. Similarly, it is also possible to engineer a crime scene. Frumkin developed a test that can differentiate real DNA samples from a fake one by detecting epigenetic modifications such as methylation. Seventy percent of the human DNA is methylated; Scientists for example would be able to associate methylation at the promoter region with gene silencing.
The DNA in our cells makes us unique. It determines the colour of our skin and the size of our shoe. Just as our DNA determines our hair and eye colour our spiritual DNA which we do not inherit but cultivate by understanding our true nature determines our spiritual identity, the gifts we have for humanity and our calling in life.
