The Kent family of an Oxford professor arrested on suspicion of murdering his colleague said he was "a very quiet man who keeps himself to himself".

Maths lecturer Dr Devinder Sivia, 49, was said to be "best friends" with Professor Steven Rawlings, 50, who died of a heart attack at Dr Sivia's bungalow.

The two men were colleagues in the astrophysics department of Oxford University and were friends for more than 15 years, co-authoring an academic text in 1999.

Prof Rawlings' body was found in Southmoor, Oxfordshire, on Wednesday night.

Detectives have released Dr Sivia on bail while they investigate the death.

"they were very, very good friends…” – gurbakhsh sivia

Dr Siva's father, retired maths teacher Gurbakhsh Sivia, 80, spoke of his shock at his home in Peacock Street, Gravesend, today.

He said: "It is a shock, it is a tragedy. It is hard to believe and hard to understand what happened.

"They were very, very good friends. No one is allowed to see him but Devinder rang me from the police station last night.

"He only said 'Dad, there has been a tragedy and I am in police custody under suspicion. It is is being investigated. Hopefully it will be sorted out.'

"He is shocked himself. He was his best friend. Apparently he asked his neighbours to call the police. It is a tragedy - how it happened, I don't know.

"He said nothing of a fight or a falling out. I can't believe they would have fallen out. They were very good friends. When my friend was not feeling well Steven used to come round with flowers and food - they were like brothers.

"They wrote a book together. They have been friends since they were students at Cambridge University, I think for more than 20 years.

"It is just unimaginable. I don't know what happened - it is really shocking. "