New Delhi, Oct 6 (IANS) Activists who fought for justice in the Priyadarshini Mattoo murder case Wednesday voiced disgust after the Supreme Court reduced the killer's death sentence to life imprisonment, and asked the CBI to submit a review petition.

"We are dismayed," Aditya Raj Kaul, who led a campaign in the case since 2006, said after the Supreme Court commuted the death sentence of Santosh Kumar Singh, son of a former police officer, to life imprisonment in the 1996 rape and murder of Priyadarshini. Singh had been sentenced to death by the Delhi High Court in 2006.

Kaul said: "The high court verdict had all the points that Santosh Singh stalked Priyadarshini, molested her, then brutally raped and murdered her. We really thought the high court's verdict would be upheld.

"The CBI must submit a review petition in the Supreme Court for death penalty. If that is not possible, then the Mattoo family will seek legal counsel," Kaul told IANS.

Sharmila Singh, a student activist, said she was shocked.

"I am shocked, disappointed and dismayed. How can the Supreme Court reduce the death penalty to life sentence? If this is not a rarest of rare case and calls for a death sentence, then what is?" she said.

Harish Salve, a student who had participated in a candle light vigil for justice in the case and has been keeping a close watch on developments, said: "I hope Priyadarshini's family gets justice. If need be, we will get down on the roads again to demand justice."

However, Kaul said he is not planning to organise any protest march as yet.

"This verdict has shaken the conscience of the country. However, getting down to protest every time is not a good trend... In fact there should not be a need to do that every time," he said.

Singh was Priyadarshini's senior in Delhi University and had murdered her in her uncle's flat in Vasant Kunj in south Delhi.