Ram Singh's death in India's most secure jail is a huge embarrassment for the authorities |
Ram Singh was found dead in his shared cell at Tihar jail on Monday.
Prison officials say they believe he hanged himself. Defence lawyers and his family allege he was murdered.
Mr Singh was one of five men being held in the case, which outraged India. They all deny the charges. A sixth suspect is being tried by a juvenile court.
India's home minister Sushil Kumar Shinde said the death was a major lapse in prison security. An investigation is under way.
Mr Singh's body was released to his family at the All India Institute of Medical Sciences (AIIMS) on Tuesday afternoon after his post-mortem. The results have not been released.
His body was loaded onto an ambulance and taken away by the family, reports said.
"My brother was murdered. I have seen injury marks on the
body and finger marks on the throat," the Press Trust of India quoted
his brother as saying.Mr Singh's death has come as a huge embarrassment for the authorities who are already under enormous pressure over the case.
Tihar jail officials said Ram Singh appeared to have hanged himself with an improvised rope made from a blanket at about 05:00 local time on Monday (23:30 GMT Sunday) while his three cellmates were asleep.
Jail spokesman Sunil Gupta said Mr Singh had not been on suicide watch.
Ram Singh and the four other adult defendants - his brother Mukesh, Pawan Gupta, Vinay Sharma and Akshay Thakur - have been on trial in a fast-track court. Reporting restrictions mean few details of the trial have been made public.
They accused face 13 charges, including murder, gang rape, kidnapping and destruction of evidence. If found guilty they could face the death penalty.
Ram Singh's parents say he was threatened in prison |
The maximum sentence the juvenile would face if convicted would be three years in a reform facility.
The 23-year-old rape victim, who has not been named for legal reasons, was with a male friend when she was attacked on a bus and thrown from the vehicle on 16 December.
She died in a Singapore hospital on 29 December from massive internal injuries.
Ram Singh was accused of being the driver of the bus.
The case provoked nationwide protests and demands for tougher penalties for rapists, as well as greater protection for women.