Delhi Police on Saturday invoked murder charges against the six men allegedly involved in the gang-rape of a 23-year-old girl in a moving bus after she died in a Singapore hospital and decided to file the charge sheet in court on January 3.
Police said it will be their endeavour to ensure the "harshest punishment in the book" to the culprits.
"We hope to file the charge sheet by the 3rd of Jan, 2013. Section 302 of IPC, which is the penal section for murder, has been added in the case," Dharmendra Kumar, special commissioner of police (law and order), said.
He said a special public prosecutor of eminence has been appointed to conduct the trial in a fast track court on a day-to-day basis.
"It will be our endeavour to ensure the harshest punishment in the book to the culprits," he said.
The autopsy of the victim was done by a Singaporean medical team and the report will be made available to investigators at the earliest.
"In this moment of national grief following the loss of a young and innocent life to a barbaric crime, we appeal to members of public to stay calm and maintain peace."
"We, in Delhi Police, as citizens of this country are equally saddened, if not more. Our sympathy goes out to the bereaved family," he said.
Police had initially booked the six men under sections 307 (attempt to murder), 201 (destruction of evidence), 365 (kidnapping or abducting), 376 (2)(g) (gang rape), 377 (unnatural offences), 394 (hurting in committing robbery) and 34 (common intention) of the Indian Penal Code.
The girl had boarded the bus, thinking it to be a legitimate public carriage, from Munirka but was attacked and gan-raped even as her male friend accompanying her tried to protect her.
He was also injured in the incident.
The arrested persons are driver Ram Singh, his brother Mukesh, Akshay Thakur, Pavan and Vinay.
The sixth person apprehended claimed that he is a minor and police have sought the court's permission to get a bone test to ascertain his age.