Parents of the December 16 gang rape victim participated in a candlelight march at Jantar Mantar in New Delhi demanding justice for their daughter.
Singh remained missing for the fourth consecutive day on Wednesday.
With the Supreme Court rejecting the plea against release of the juvenile convict, the parents of the December 16 gang-rape victim on Monday said the courts have failed them and asked how many Nirbhayas would it take for the laws to change.
Parents of the December 16 gang-rape victim on Tuesday welcomed the passage of the long-pending Juvenile Justice Bill saying that it will deter juveniles from committing such crime against women even though they rued that their daughter has been denied justice.
The victim's mother Asha Devi, in a display of extraordinary courage, took her daughter's name in public.
Scores of protesters, including the parents of the December 16 gang rape victim, were detained by the police after they staged a protest.
The juvenile convict in the December 16 gang rape was on Sunday released and sent to an NGO at an undisclosed destination with police no longer guarding him.
The verdict said that the aggravating circumstances outweigh the mitigating ones and hence, the convicts did not deserve any leniency.