New Delhi: The Supreme Court on Friday sought the assistance of senior advocates Raju Ramachandran and Sanjay Hegde to defend four convicts on death row for the 2012 Delhi gang rape-murder case.

A bench comprising justices Dipak Mishra, V. Gopala Gowda and Kurian Joseph were hearing appeals filed by the four convicts—Mukesh Singh, Pawan Gupta, Akshay Thakur and Vinay Sharma—against the death sentence awarded to them.

“We are not happy with the quality of the defence," the bench said, asking the senior lawyers to defend them.

Lawyer M.L. Sharma, who was arguing for the convicts, contested the victim’s dying declaration. The court had asked him to counter the testimony of the witness which was relied on by the lower courts.

On 4 April, the apex court began hearing the appeals after staying the death sentence of the four convicts in March 2014.

The six accused were found guilty by a Delhi fast track court. The Delhi high court upheld the death sentences on 13 March 2014.

Ramachandran has represented Ajmal Kasab, the lone terrorist arrested by the police in the 26 Novermber, 2011 Mumbai attacks that killed 166 people. Kasab was executed after the Supreme Court upheld his death sentence in August 2012.

A 26-year old physiotherapy student in Delhi was brutally assaulted by six men, including the four convicts, after she and a male friend boarded a private bus on 16 December 2012. She died in hospital a fortnight later. One suspect died in custody and another was tried and sentenced by a juvenile justice court.

The incident triggered nationwide outrage, and led to tougher sexual assault laws in the country.