Man arrested after Oxford academic is murdered in the heart of Morse country

Murder squad detectives hunting the killer of Dr Barbara Johnston, a leading Oxford academic who was stabbed 49 times and apparently strangled with her own sweater, last night arrested a 42-year-old man.

Dr Johnston's death has shocked the university city of Oxford, where the 55-year-old had been living for only four months after working for 23 years in New Zealand.

The fully clothed body of the biomedical researcher, an expert in child respiratory complaints, was found by police in her bedroom early on Thursday morning after her elderly parents were unable to reach her by telephone.

Officers had to batter down the door of her flat in Woodstock Close, which is a short drive from Oxford's colleges.

The murdered professor, who was single, also lived close to an area known for its academic community which provided a backdrop to the classic Inspector Morse mysteries.

Around her neck was the sweater which police believe may have been used to strangle her. A post- mortem examination has revealed that she died of multiple stab wounds and asphyxia. Detectives have yet to establish a motive for the murder of the woman who had no children and was described by her family as a "private" person.

Forensic examinations found no sign of forced entry to her flat, which is in a building currently covered by scaffolding. Nothing was taken from her home.

Detectives believe Dr Johnston, whose doctorate was in philosophy, may have opened the door to her killer or killers and may have known her attacker.

Thames Valley police said the investigation is now centred on her lifestyle as police try to build up a picture of her last movements.

An entry posted on the Friends Reunited website under her name in November 2001 tells how "safe" she felt in Auckland.

"Can't afford to return to the UK while it's so expensive to live there," the entry says, "But life in the South Pacific is relaxed, peaceful and safe, which must count for something these days."

Acting Detective Superintendent Steve Tolmie, who is leading the murder hunt, saidhe would investigate whether Dr Johnston, who had few known friends, had been in contact with people through the internet.

It is understood that Dr Johnston studied at Southampton University and was also a graduate of Somerville College, Oxford, which is where former Prime Minister Margaret Thatcher obtained her chemistry degree in 1947.

In September last year, Dr Johnston returned to the UK because it is thought a research project in New Zealand ended. At the time of her death, Dr Johnston was unemployed.

Acting Det Supt Tolmie said that officers estimated that the attack took place some time between Monday afternoon and 1am on Thursday morning, the time police forced entry to Dr Johnston's home.

It is understood that she had ordered a new freezer for her parents in the West Midlands, but had not been in contact to find out if it had arrived. Her last telephone call was on Monday afternoon when she spoke to a letting agent.

Acting Det Supt Tolmie said: "We are trying to develop a knowledge of her life. We need to know of anyone who knew of Dr Johnston in any capacity to help in our investigation of this shocking crime. This is a tight-knit community and I'm hopeful that someone comes forward with vital information."

Neighbours told of their shock and horror at the killing in the flat which sits in a green and secluded cul-de-sac.

Retired physiotherapist Hannekeh Cott said: "We have never had anything [like it]. About 10 years ago we had a burglar, I think, who escaped and ran through the gardens at the back, but that's all we've had."

Mr Tolmie urged anyone who may have seen anything suspicious in the area to call Thames Valley police's police inquiry centre on 08458 505505 or Crimestoppers, anonymously, on 0800 555111.

He added: "I would also personally appeal to anyone who believes they know the killer's identity or if they have any concerns not to hesitate but to contact the incident room immediately.

"The attacker or attackers would probably have had blood on their hands or clothing or may have been acting in a different manner. If you have any suspicions, contact us."

An incident room has been set up at Loddon Valley police station in Earley, Reading.