Although tests like brain mapping and polygraph help widen the scope of a criminal investigation, their results are not admissible in the court of law.
The Vyapam case has put spotlight on use of modern forensic techniques for identifying the perpetrators of crime. Credit: PTI
The CBI recently decided to send a team to Bhopal to put several of the suspects in the Vyapam admission scam through a polygraph (lie detection) test by the end of September, in order to give them a chance to prove their “innocence.” This has brought into the spotlight the issue of scientific evidence and its admissibility in the court of law.
Senior police officers and forensic experts believe that even if tools like polygraph test, narco analysis and brain mapping may not be completely admissible in the court of law, they remain important investigative aids and the response of the suspects towards them is sufficient to draw inference about their conduct.
The CBI has decided to conduct polygraph tests on those suspects who gave their consent to voluntarily undergo these tests to prove their innocence. Many of these suspects are students who were rusticated from colleges after they had allegedly cleared the pre-medical tests using unfair means.
The important part is that the CBI has not forced any of the suspects to take these tests. The law pertaining to the use of polygraph is very clear – the authorities cannot subject any accused or suspect to undergo narco analysis, brain mapping or polygraph tests forcibly.
In May 2010, the Supreme Court held that forcing suspects and witnesses to take these tests without their consent was unconstitutional and amounted to violation of their right to privacy.
A three-judge bench had held that “the compulsory administration of the impugned techniques violates the right against self-incrimination.”
On the admissibility of the tests, it stated that, “results cannot be admitted in evidence if they have been obtained through the use of compulsion. Article 20(3) of the constitution [No person accused of any offence shall be compelled to be a witness against himself] protects an individual’s choice between speaking and remaining silent, irrespective of whether the subsequent testimony proves to be inculpatory or exculpatory.”
Giving reasons behind its ruling, the bench said: “Article 20(3) aims to prevent the forcible conveyance of personal knowledge that is relevant to the facts in issue. The results obtained from each of the impugned tests bear a testimonial character and they cannot be categorised as material evidence.”
In all these tests, the results rely on the records of the physiological responses of the suspects or witnesses to narco analysis, brain mapping or polygraph test. The bench had stated that while forcible use of these techniques would violate Article 20(3), even in cases where the subject decided to undergo these tests voluntarily, the result themselves could not be admitted as evidence.
“The subject does not exercise conscious control over the responses during the administration of the test. However, any information or material that is subsequently discovered with the help of voluntary administered test results can be admitted, in accordance with section 27 of the Evidence Act,” the bench had clarified.
According to senior police officers and forensic experts, irrespective of whether the courts recognise these test, they remain effective tools in developing a line of investigation.
When asked why the CBI or other agencies still rely on these tests despite the courts not accepting them as conclusive evidence, former CBI director Joginder Singh said, “It is for the simple reason that these tests would reveal what would otherwise probably not come out in any way. It is an aid to investigation.”
Adding that “sometimes these tests help” in disclosing important pieces of information about the case, he said, this helps widen the investigation as the names of more people are revealed. “They may lead to a clue. They may add to the linkage sometime, but sometimes the persons conducting these tests also may be compromised.” Hence, he suggested observing caution while using these tests.
Instances of use
In India, forensic tests have been used in several high profile cases; for instance, in the Rs 3,000 crore stamp paper scam, mastermind Abdul Karim Telgi was subjected to a truth serum or narco analysis test, the P-300 brain mapping test and a polygraph test by the Maharashtra police.
The special investigation team, which was constituted to probe the case, had used these tests to establish the culpability of those behind the scam, as a number of police officers were found guilty of accepting money from Telgi, while little information was being revealed against the actual perpetrators.
In the sensational Aarushi-Hemraj murder case, the CBI had subjected her parents Rajesh Talwar and Nupur Talwar to a polygraph test in 2008. Three men, Krishna, Raj Kumar and Vijay Mandal – all servants from their neighbourhood – were also put through the test.
In his book, Aarushi, journalist Avirook Sen, who had covered the murder as a crime reporter, had pointed out that these tests had yielded startling results. In 2015, a news portal reported that “Talwars showed no awareness of the crime. However, the three servants gave a blow-by-blow account of their presence in the house, their involvement in the crime and the motivations driving them.”
The Talwars were, however, still convicted for the crime and are today languishing in jail. “These tests are not legally admissible. However, they are important indicators for which way a line of investigation can develop. The tests were also particularly important because it led to the recovery of a possible murder weapon: a khukri, from one of the friends’ room. However, these transcripts were never made public. When the second CBI team took over, inexplicably, the servants were instead completely dropped from the trial as possible suspects,” the report had said.
In the Nithari case, in which skeletons of 17 missing children were recovered from inside and near a house in Noida, house owner Moninder Singh Pandher and his servant Surinder Koli were arrested and were made to undergo brain mapping and polygraph tests in 2007.
After the tests, the police had stated that Koli had confessed to the crimes, but had given Pandher a clean chit saying that he was unaware of Koli’s doings. Koli had alleged sexually assaulted, murdered and dismembered most of his victims. He was subsequently convicted of five murders and sentenced to death, but the Supreme Court later changed it to life imprisonment. Pandher was, however, acquitted by the high court.
Writing on the issue, Mukesh Yadav, the editor of the Journal of Indian Academy of Forensic Medicine, had pointed out that modern forensic techniques such as brain mapping, polygraph test, narco analysis and functional MRI are quite useful in revealing the truth from the accused.
“The term narco analysis is derived from the Greek word narke meaning ‘numbness’ and is used as a psychotherapeutic as well as interrogating technique that uses barbiturates drugs or truth serum to induce a state of unconsciousness in which secrets come to the surface since the person testifying is not in control of what he says,” Yadav said, adding that nowadays sodium pentothal is widely being used as a truth serum.
Stating that the “truth serum test is not legally admissible evidence in India”, Yadav wrote that it “can be used by interrogating agencies for further investigation purposes after court’s permission.”
Similarly, in case of a polygraph test, or ‘lie detection test’, he said, it is a device that measures and records several psychological variables such as blood pressure, heart rate, respiration and skin conductivity while the subject is asked a series of questions. Underlying this test is the ancient hypothesis that a person experiences nervousness while telling a lie.
While the accuracy of the polygraph has often been contested, a person who had undergone the test told The Wire that during its conduct, the investigating agency provides a list of questions and information about the subject to the technician. “It catches every lie. Even if they hand you pieces of paper with numbers one to ten written on them and you try saying the wrong one for any one, the machine detects it. Similarly it catches every small lie, whether it is related or not to the investigation.”
But, as Yadav wrote, these tests are still not admissible in the courts of law in India. As for brain mapping or brain fingerprinting technique for detection of lies, he said, “this EEG/P300 wave-based system determines whether or not specific information is stored in a person’s memory. The test measures individual brain wave responses to relevant words, pictures or sounds presented by a computer. Our brain stores events as memories. This function of the brain is used in differentiating a criminal and an innocent person. The criminal’s brain stores the sequence of events that happens at the crime scene. An innocent man’s brain, however, would have no such memories.”
Therefore, “the brain mapping method scientifically detects the presence or absence of specific memories in the brain. Words, pictures, codes and sounds related to the crime are presented to the subject by a computer. The brain wave responses to these stimuli are measured using a headband equipped with EEG sensors. The data is then analysed to determine if the relevant information is present in the memory.” But this method too is not admissible.
The other technology that is now being used to arrive at the “truth” is a functional MRI (fMRI). It works on the notion that the frontal lobe area of the brain becomes more active when a person is telling a lie. The fMRI scans the brain to find which areas were active in particular circumstances and hence can help determine whether a person is telling the truth or lying.
While the technologies continue to provide the investigators with relevant leads – even if not solid conclusive evidence – it is high time they are fine-tuned to enable agencies to quickly and honestly sift the innocent from the culprits.
