Man questioned over stab murder

Dr Johnston had lived in New Zealand for 23 years

Police hunting the killer of a scientist stabbed 49 times have been given more time to question a man.

Barbara Madeline Johnston, 55, was found dead at her Oxford home, off Woodstock Road, early on Thursday.

Post-mortem tests showed Dr Johnston, a medical researcher, had died of multiple stab wounds and asphyxia.

Her parents, from the West Midlands, said they were devastated. A 42-year-old man was arrested at an address in Faringdon on Saturday.

She was an intelligent, lively and a devoted daughter and she will be greatly missed by us all Dr Johnston's parents

Police have until Monday evening to question the man, who is being held at Abingdon Police Station, after being given a 24-hour extension.

Dr Johnston had only lived in the flat since September as she had been living in New Zealand for the previous 23 years.

Police said earlier they had not yet found a motive for her murder.

Det Ch Insp Steve Tolmie said Dr Johnston's parents had raised the alarm on Wednesday after becoming concerned for her welfare as they had not heard from her.

In a short statement her parents, Anthony, 80, and Valerie, 79, and her brother Patrick, described her as "dearly beloved".

Dr Johnston's parents called police after they could not contact her

They said: "We are all devastated by her tragic and untimely death and ask that our privacy be respected at this terrible time.

"Barbara was a dedicated research scientist who strove to forward work in the field of cot death and premature babies.

"She was intelligent, lively and a devoted daughter and she will be greatly missed by us all."

Police revealed yesterday that there were no signs of forced entry, leading detectives to believe she may have opened the door to her killer.

It is thought the murder weapon was a singled-bladed knife.

Det Ch Insp Steve Tolmie said: "I appreciate that this is a worrying time for the people living in this area but would like to reassure them that a full investigation is under way and together with help from the public we can bring whoever is responsible to justice."