Dr Michael Meenaghan's last breaths were heard by emergency operators after he dialled 999, but he had died from massive chest injuries by the time police smashed their way into his home. He had not been able to give any clues as to his assailant.
A lecturer at the Sir William Dunn School of Pathology at Oxford University, Dr Meenaghan, 35, was shot at about 4.30pm at his end- terrace home on the Blackbird Leys estate in Oxford. Police called it an apparently motiveless attack.
Neighbours in the street of smart private houses said the lecturer had appeared nervous recently and had taken to drawing his curtains day and night.
He had draped a sheet across an upstairs window, apparently as an extra precaution against being seen.
Officers at the scene on Saturday said all Dr Meenaghan's doors had been locked from the inside. He had made his telephone ex-directory within the past 12 months, yet initial inquiries into his private life are understood to have found nothing other than"exemplary" behaviour, according to one senior officer.
"We're going to have our work cut out to even find a motive," said the officer. "There is nothing to indicate why Dr Meenaghan was murdered or to suggest why anyone would want him dead."
There was speculation last night that the killing had the hallmarks of an ordered "hit" but Detective Superintendent Jon Bound, who is leading the inquiry, was keeping an open mind.
Detectives are understood to have studied a number of letters that may have thrown light on several relationships Dr Meenaghan had had with women. He was living alone at the time of his death.
Mr Bound said that the kitchen window of the Monks Close house had been broken, suggesting either that the attacker first smashed it before shooting Dr Meenaghan or that the gun was fired straight through it.
He said a 999 call was received after the shooting and added: "The emergency call was passed over to the police. No speech was heard but someone struggling for breath could be heard in the background. Police went to the house and it appeared secure. Looking through the kitchen window, a man's body was seen lying on the floor.
"Officers forced their way in and the lifeless body of Dr Michael Meenaghan was found. A telephone in the kitchen was found to be off the hook and the victim had been shot through the chest."
A post-mortem examination held at the John Radcliffe Hospital confirmed the cause of death as a haemorrhage of the chest.
Dr Meenaghan, a Scot, was believed to have had only one living relative, an elderly mother who is said to be in extremely poor health. She has been told of his death by police.
Oxford University refused to discuss the murder yesterday, but Tim Beesley a fellow academic at the School of Pathology, said Dr Meen-aghan, nicknamed "Spike", had spent the past four years researching molecular biology.
He said: "I am stunned by what has happened and just can't take it in. The circumstances of his death are very strange and I can't think what is behind it. His research was quite straightforward and certainly not controversial.
"I was only speaking to him on Friday so this is a terrible shock. He came in to work in the morning and we chatted and passed the time of day. I saw him again when I left in the afternoon and he just seemed his normal self.
"Spike was quite a character and well liked in the department. He was originally from Glasgow and had a great sense of humour. I wasn't a close friend but he didn't seem to be troubled or to have any particular personal problems."
Neighbours of the lecturer described him as a pleasant quiet man who wore his grey hair in a ponytail and chatted regularly to local children.
One, who asked not to be named, said he had worked for several months with Dr Meenaghan at the school of pathology.
He said: "I didn't get to know him very well but he always seemed like a very nice bloke and would always say hello. He always seemed pretty cheerful. He was the last person you would expect anyone to attack - it's a real mystery."
Henry Sherriff, who lives four doors away, said: "I can't think why anyone would have wanted to shoot him.
"He was a very pleasant man who often chatted to our kids. I can't imagine him having any enemies."