One of the four rapists who attacked a student on a bus in 2012 has lost his appeal to avoid the death penalty.
Pawan Kumar Gupta filed an appeal after all four of Jyoti Singh's attackers were sentenced to hang.
Jyoti's mother, Asha Devi, said outside court: "Their tactic to delay hanging has been rejected. I'll be satisfied only when they're hanged on Feb 1.
"Just like they're delaying it one after other, they must be hanged one by one so that they understand what it means to toy with law."
The four men, named Akshay Thakur Singh, Mukesh, Pawan Gupta and Vinay Sharma, lured the physiotherapy student Jyoti and her male friend on to a bus.
They then severely beat both victims before dumping them naked and semi-conscious on the roadside in Munirka, in the south of the city.
The woman died in hospital weeks later, in a high-profile case that sparked global outrage and widespread protests in India about violence against women in the country.
After years of legal wrangling, they are due to hang on January 22 at 7am local time, according to India Today.
Part of Pawan Kumar Gupta legal argument against his death sentence was the fact he was a juvenile when he took part in the sick attack.
The Supreme Court ruled that the accused was entitled to raise the point about their age at any point under Juvenile Justice Act - but the plea again and it was dismissed.
Originally six men who were on the bus including the driver were arrested.
One suspect man died in hospital in a suspected suicide, although his family have claimed he was murdered.
A juvenile was convicted of rape and murder and given three years' imprisonment.
The death warrants come after a series of reviews from the convicts, including rejecting Akshay's plea for mercy.
The case sent shockwaves around the world, and sparked mass protests that saw outraged locals clash with security forces in India, where women and their supporters took to the streets to demand change.
The protests led to silent marches around the country, where women fear for their safety amid widespread sexual violence.
The victim came to be known in India as Nirbhaya, a Hindi word meaning "fearless", as Indian law does not permit the press to publish a rape victim's name, although her parents later requested that her real name be used when a museum was dedicated in her honour.
Jyoti's death also became the flashpoint for a wider rallying cry to stop sexual violence against women globally.
The case also led to global scrutiny of India's justice system, and accusations its Parliament had been slow to respond to the crisis of violence against women.
Weeks after Jyoti's death, one of the defendant's lawyers had publicly suggested that the victims should not have been using public transport as an unmarried couple.
He reportedly said rape did not happen to "respectable" women and blamed her male companion for failing to protect her.
