The widow of tragic Oxford professor Steve Rawlings said she did not believe his best friend was responsible for his death.

Dr Devinder Sivia, 49, was arrested on suspicion of murdering Prof Rawlings after the 50-year-old’s body was discovered at the former’s home in Laurel Drive, Southmoor, on Wednesday night.

Dr Sivia – a friend of Prof Rawlings for more than 30 years – was released on police bail yesterday after a post mortem examination could not determine what killed the astrophysicist.

Detectives indicated Dr Sivia may be cleared of any responsibility, while Prof Rawlings’s wife Linda said she did not believe the St John’s College mathematician had murdered the man she described as the love of her life.

She said: “Steve and Devinder were best friends since college and I believe this is a tragic accident.

“I do not believe that Steve’s death is murder and I do not believe Devinder should be tarnished in this way.”

Friends of Prof Rawlings said he had suffered psychiatric problems a year ago, and was distressed and contemplating quitting his job at St Peter’s College on the day of his death.

He went to Dr Sivia’s home that evening and at 11.22pm police and paramedics were called to the bungalow. Resuscitation attempts to save the scientist failed.

Mrs Rawlings was away on business at the time and rushed back to the couple’s home in Letcombe Regis.

Yesterday she said: “Steve was a well-loved, caring, intelligent, sensitive man.

“Steve is a man of integrity, kindness and a very accessible person.

“He was the love of my life and we have known each other all of these years and he has never changed, even though he has achieved so much and has all these qualities.

“I will miss him more than anything else in the world.”

Detectives are still trying to piece together exactly what happened inside the bungalow, but Det Supt Rob Mason said: “This is a tragic incident and our investigations are on-going to establish the cause of death.

“Police are investigating all potential circumstances that could have led to his death. We are mindful that ultimately the death may be a matter for a coroner’s inquest rather than a criminal court.”

A close friend told how the professor had talked to him at length just hours before he died.

He said that he appeared very troubled and that he had been talking of resigning from Oxford University. He said he was going to seek further advice from his close friend and fellow Oxford don, Dr Sivia.

He added: “He knocked on my door and wanted to chat. This must have been around 4pm on Wednesday.

“I could tell he wanted to get some things off his chest.

“He had a very intense job and he was a very intense person.

“He had had a breakdown last year and on that occasion was found wandering around the village in his dressing gown in the middle of the night.”

In Letcombe Regis, friends who knew Prof Rawlings at local pub, the Greyhound Inn, were still coming to terms with the news of his death yesterday.

A regular at the pub, known to other customers as “Moppy”, said: “He was a very nice fellow.

“We had a drink for him last night.”

The Department of Physics described Prof Rawlings as “not only an excellent scientist but also a dedicated tutor and mentor”.