New Delhi: Scientific and forensic evidence like DNA, fingerprints and bite marks analysis, on Friday sealed the fate of the four convicts in the December 16, 2012 gangrape and murder case as the Supreme Court termed them accurate.
The top court said while while DNA report "cogently linked" each of these accused with the victim and the crime scene, the fingerprint analysis "incontrovertibly proves" that one of the convicts, Vinay Sharma, was present in the bus at the time of the barbaric incident.
Regarding Odontology, a branch of forensic science on bite mark analysis, a bench headed by Justice Dipak Misra said the report placed on record was "wholly credible" because of the matching of bite marks with the tooth structure of the convicts and there was no reason to view them with any suspicion.
The bench, also comprising Justices R Banumathi and Ashok Bhushan, said DNA technology not only provided guidance to investigation, but also supplied the court accrued information about the "tending features" of identification of criminals, and such evidence was increasingly relied upon by the courts.
The apex court, which upheld the death sentence awarded to the four convicts - Pawan Kumar Gupta, Vinay Sharma, Mukesh and Akshay Kumar Singh -- said the recent advancements in modern biological research has regularised forensic science resulting in radical help in administration of justice.
"The DNA profiling, which has been done after taking due care for quality, proves to the hilt the presence of the accused persons in the bus and their involvement in the crime.
The submission that certain samples were later taken from the accused and planted on the deceased to prove the DNA aspect is noted only to be rejected because it has no legs to stand upon," it said.
The bench noted that there were various "white bite marks" on the victim's body and such analysis report plays an important role in the criminal justice system.
The apex court said "there is no reason to declare the DNA report as inaccurate, specially when it clearly links the accused persons with the incident".
The bench also said that in India, like other countries, DNA evidence was increasingly being relied upon by the courts and after 2005 amendment in the Criminal Procedure Code, DNA profiling has now become a part of the statutory scheme.
Referring to various apex court verdicts, the bench said "it is quite clear that DNA report deserves to be accepted unless it is absolutely dented and for non-acceptance of the same, it is to be established that there had been no quality control or quality assurance."
"If the sampling is proper and if there is no evidence as to tampering of samples, the DNA test report is to be accepted," it said.
In its judgement, the apex court said that to establish aclear link between the convicts and the incident, the police has adduced scientific evidence like DNA, fingerprint and bite mark analysis.
The court noted that various samples from clothes, iron rods, ashes of partly burnt clothes and the bus were lifted from the victim and the convicts during the investigation.
"After establishing the identities of each of the accused persons, the informant (victim's friend) and the prosecutrix (victim) through DNA analysis, the DNA profiles generated from the remaining samples, where the identity of biological material found thereon needed to be ascertained, were matched with the DNA profiles of the prosecutrix, the informant and the accused, generated earlier from known samples," it noted.
"Such an analysis cogently linked each of the accused with the victims as also with the crime scene," it said.
The bench referred to the statement of Dr BK Mohapatra, one of the prosecution witnesses in the case, and said he has testified that once a DNA profile was generated, its accuracy is 100 per cent.
The apex court observed that the defence counsel had not raised substantial grounds to challenge the DNA report during the cross-examination of Mohapatra before the trial court and there was "no reason to declare the DNA report as inaccurate" especially when it clearly links the convicts with the crime.
It also dealt with the contentions of defence counsel who had argued that DNA test cannot be treated as accurate as the victim had undergone blood transfusion during the treatment and when there was mixing of blood, DNA profiling was likely to differ.
The apex court referred to its previous verdicts and said if quality control was maintained, DNA profiling was treated to be quite accurate.
It also referred to the apex court's verdict in the case of 26/11 attack convict, Mohammed Ajmal Amir Kasab, and said in that case too, DNA test had matched with stains of sweat, saliva and other bodily secretions on the articles recovered from the accused.
Dealing with the bite mark analysis report, the bench said it linked Ram Singh (since deceased) and convict Akshay Kumar Singh with the crime.
"The photographs depicted the bite marks on the body of the prosecutrix. The said bite marks found on the body of the victim were compared with the dental models of the suspects.
"The analysis showed that at least three bite marks were caused by accused Ram Singh, whereas one bite mark has been identified to have been most likely caused by accused Akshay," the bench noted in its order.
The court also referred to the technological advancement, like laser scanning, scanning electron microscopy or cone beam computed tomography in forensic odontology, which are utilized to identify more details in bite marks.
"Unlike fingerprints and DNA, bite marks lack the specificity and durability as the human teeth may change over time. However, bite mark evidence has other advantages in the criminal justice system that links a specific individual to the crime or victim," it said.
The bench also rejected the contentions of the defence counsel that the bite marks were stage-managed.
Regarding finger print analysis, the bench said it had clearly established that Vinay was present in the bus at the time of the incident while "other chance prints were found to be unfit for comparison or different from specimen print".