Public prosecutor Rajiv Mohan told a judge that five suspects attempted to destroy evidence by burning their clothes, but the burnt material still showed traces of the victim's blood.
The Observer said the men charged with rape and murder will appear in court for the first time Monday since the incident three weeks ago. The men face the death penalty.
The Observer said the victim died in a Singapore hospital two weeks after the attack, which took place on a bus.
The victim's friend said she was raped for more than hour and suffered internal injuries after an assault with an iron bar.