They pasted posters for the campaign in the campus between 8-11 p.m. Thursday.

Barely hours later, Singh's body was noticed in the Maurice Nagar area near Khalsa College by a passer-by.

'It was shocking. Pooja, I and Parminder were sticking posters in the Delhi University area inviting people to join us in a candle light vigil to seek justice for Professor Sabharwal. A student leader of Ramjas college also joined us later,' Himanshu said.

'After that, we went our way. I dropped Pooja en route and reached home at 12.45 a.m. Around 1 a.m. I got a call from Parminder's wife who said that he had not yet reached home. He was on his bike. I told his wife that he should be home soon,' he added.

When he finally got to know about Singh's death, Himanshu was updating his blog on Facebook, writing about his father.

A portion of his updated blog read: 'On the 26th of August, 2006, this man was killed in cold blood after his face was smeared with mud, his clothes torn and he was kicked and boxed in the chest which broke his ribs and punctured his lungs. I saw his body on the 27th, blue and black in the mortuary with eyes static in oblivion. For this man, I demand justice.'

Coming back to the issue of Singh's murder, in relation to which Himanshu has been questioned by police, he said: 'I was shocked. Parminder was a harmless guy, he couldn't have animosity with anyone.'

'In these three years I have seen so much dirt around...it's just unimaginable. First my father and then Parminder. Now some sections of people are trying to malign me. It just takes a toll on me at times,' he wrote.

'But I have seen the system so close that I can't ignore it. I have to go on,' Himanshu told IANS, adding he has 'reached the point of no return'.