Manohar Lal Sharma also accused authorities of tampering with evidence. "They are innocent," Mr Sharma said of his clients ahead of a court hearing.
He also claimed police beat the men and placed other prisoners in the suspects' cells to threaten them with knives.
Five men have been charged with attacking the 23-year-old woman and a male friend on a New Delhi bus.
The woman was raped and assaulted with a metal bar on December 16 and died of her injuries. Rape victims are not identified in India, even if they die.
The case has sparked protests across India by those who say its legal system does not do enough to prevent attacks on women.