A DNA investigation of bloodstained clothes and body swabs has linked all five men and a juvenile accused of the gang rape and murder of a woman in New Delhi to the crime, providing evidence the prosecution claims will be enough to convict them.
Prosecutors say their case will also hinge on cellphone records and on testimony from the dying woman and a male companion who was attacked with her on a moving bus in the Indian capital on Dec. 16.
However, the case against the men may not be open and shut in a country where shoddy forensic practices are one of the chief reasons for a low conviction rate in rape trials.
Defence lawyers told Reuters they were preparing to reject the forensic findings as fabricated.
They said they would also contend that the case is unsafe because police rushed investigations after an outpouring of popular fury over the attack. Two of the four defence lawyers have said their clients were tortured in custody to make confessions that looked suspiciously similar.
"The statements all read the same. It is like somebody has dictated it to them," lawyer Manohar Lal Sharma told Reuters.
A police spokesman declined to comment on the confessions, saying it was policy not to respond to reported allegations.
"We have no comment to make on media reports. If anything has to be communicated, it will done in the appropriate court," he said. "We are not going to engage in a debate in the media."
Another official said the men had to undergo medical tests in custody and if they were beaten, it would have shown up; and if the lawyers were serious about the allegations, they should approach the court rather than air views in the media.
The defence will also argue that the men were denied legal aid for more than three weeks after their arrest and point to discrepancies in the account given by the woman's friend.
DNA SAMPLES - FROM CLOTHES TO DRIED LEAVES
A fast-track court will on Monday begin hearings in the case just five weeks after the attack, which brought thousands of protesters on to the streets of New Delhi and made headlines around the globe.
Police said the 23-year-old physiotherapy student and her friend were lured into the bus, both were beaten and then the woman was taken to the rear of the bus and raped. They were then thrown, bleeding, on to a dark roadside. The woman died in a Singapore hospital nearly two weeks later.
While the five men have been charged with rape and murder and face the death penalty if convicted, the juvenile will be tried separately. He will not be charged until police confirm he is under 18.
The forensic report found that DNA tests on bloodstains from underwear worn by the main accused, Ram Singh, matched those of the woman. Another test done on a swab taken from her body showed his DNA signature, according to a laboratory report seen by Reuters.
A lawyer for Singh dismissed the results as manipulated and demanded that the case be heard in a court away from the Indian capital, where pressure for a conviction is intense.
"The Delhi police are biased. This case must be taken away from Delhi," lawyer V.K. Anand said.
The other lawyer, Sharma, has filed a petition before the Supreme Court separately, asking for the case to be transferred out of New Delhi to ensure a free and fair trial.
The police spokesman declined to comment on the lawyers' claim that a fair trial was not possible in New Delhi.
The DNA samples were taken from bloodstains on clothes of all five accused, curtains and seats on the bus. Samples were also taken from bloodstained dried leaves by the side of the highway where the pair said they were dumped.
The woman's DNA profile showed up in bloodstains on the undergarments and flip-flops of Vinay Sharma, a gym assistant and one of the five men accused, a police document said.
Another test on blood found on his jacket matched that of the woman's friend, who, according to police, fought with the men before he was hit with an iron rod.
But Vinay Sharma's lawyer, A.P. Singh, said his client was not even on the bus that night. Sharma was with the main accused, Ram Singh, and his brother in the early part of the evening, but did not join the others when they allegedly went on a joy ride looking for women, the lawyer said.
"The police have falsely implicated my client. He is absolutely innocent," A.P. Singh said. "The DNA evidence against Vinay Sharma has been fabricated by the police. The police have a tendency of doing such things."
The police spokesman declined to comment on this allegation.
The police report also linked DNA evidence to the other members of the group - Ram Singh's brother, Mukesh Singh, 26, bus cleaner Akshay Kumar Singh, 28, and fruit vendor Pawan Kumar, 19, all of whom it says were friends who gathered for dinner that night and carried out the assault.
"All we need is to establish one member of the group committed the crime of rape. We don't have to prove every one of them did it," said the prosecution source.
Under Indian rape laws, all members of a group are equally liable as long as one is proved to have committed the crime.
Cellphone records show that both Vinay Sharma and Pawan Kumar received calls between 9:24 p.m. and 9:54 p.m., the period of the attack. These corroborated their location in south Delhi areas that the bus passed through at that time, according to the police document, which gave details of the calls on each phone.
The woman's friend also received a text message and a call during the time of the attack, but he couldn't answer because the phone had been taken away, police said. Closed-circuit TV footage of the street outside from Hotel Delhi Airport near where the pair were left also showed that the bus crossed the area twice, police said.
According to Ram Singh's statement to police, the group washed the bus after they returned home that night and set fire to clothes torn off the couple. Two neighbours in their slum who police said saw them burning the clothes are among 80 prosecution witnesses.
The prosecution says it will point to articles stolen from the couple on the bus, including their cellphones, rings and debit cards, the man's watch and shoes and all their money. Most of these were found in raids conducted in the men's homes, the police document said.
The defence lawyers, for their part, will zero in on discrepancies in the friend's version of events.
The friend told a television network that he and another friend lay naked and bleeding for 45 minutes in the street after the attack. When a police van arrived, officers spent a long while arguing about under whose jurisdiction the crime fell.
But Delhi police say GPS records showed the first police van reached the scene four minutes after they were called and took the battered pair to hospital within 24 minutes.
"When they cannot agree on such basic things, then how can you trust them on the main charges?" said lawyer Sharma, who is defending Mukesh Singh, the man police say drove the bus for most of the time while the others attacked the woman.
He said his client had not even read the charges against him because much of the charge sheet he was handed was only in English, which he cannot read.
"They have collected the evidence, they have already pre- decided that these are the accused persons and they have created the evidence against them," the lawyer said. "Within 10 days they completed everything. Has anything ever happened in India so fast?
India's criminal justice system is widely seen to have failed women who are sexually assaulted. One woman is raped every 20 minutes in India, according to government statistics, but the conviction rate is among the lowest in the world and one of the key reasons is lack of proper investigation.
An August 2012 study of 40 judgments of rape cases by district courts in Delhi where the accused were acquitted found that more than half were due to police failure to perform adequate investigations.
The study, by the Delhi-based charity Shakti Vahini, cited examples where judges criticised investigating officers for not collecting evidence or finding witnesses to support the claims.
Police refused to be drawn into comment on the pace at which they had moved in the latest case and on the issue of the language of the charge sheet. But K.T.S.Tulsi, a prominent criminal lawyer, said the court can provide a Hindi translation of the charge sheet if the accused asked for it.