Police investigating the murder of a nurse found beaten to death in her family home 25 years ago have made a fresh appeal for information in a bid to finally bring her killer to justice.

Janet Brown, 51, was found at the foot of the stairs with fatal, blunt-force head injuries on 10 April 1995 at her home in the quiet village of Radnage in Buckinghamshire.

The mother-of-three was naked, with her arms handcuffed behind her back and her mouth gagged with packing tape. The victim had suffered four or five blows to the head from a weapon such as a crowbar.

Nothing was taken from the detached house on Sprigs Holly Lane, and although Brown was found naked, there was no evidence she had been sexually assaulted.

The method of entry has also confused police, with the killer trying to cut a man-sized hole out of a double-glazed patio door using a glass cutter - an incredibly time-consuming and difficult process. Eventually, they just smashed their way through.

In 2015 officers from Thames Valley police’s major crime investigation review team revealed they had obtained a DNA sample believed to be that of the killer.

Five years on, more than 700 men have been screened – almost every male in the surrounding area – and it has still not led to an arrest.

The chief investigating officer, Peter Beirne, said: “My working hypothesis at the moment is that it was a burglar, or burglars, who weren’t particularly proficient.

“They came across Janet, they had control of her because they handcuffed her, and I think she was bludgeoned to death when she pressed the panic alarm.”

Brown had been alone in the house on the night of her death.

Her eldest daughter, Zara, then 22, had moved to London while her son Benedict, 21, was away at university and her youngest daughter Roxanne, 17, was staying with a friend.

Her husband, Dr Grahaem Brown, worked in Switzerland for a drugs company and was usually away during the week.

Beirne said his team are still working their way through the list of people who featured in the original investigation. He estimates there is still about 20% of the list to go.

Investigators also recognise the very real possibility that 25 years on, Brown’s murderer may be dead. “That in itself isn’t a problem for us,” Beirne said.

“If people have got suspicions, if they just let us know who that person was we can research that person, find out whether they featured and what their background was.

“Then we will make a decision as to whether we should pursue looking at a close male relative of that person for a DNA swab, in which case we would be able to certainly eliminate them from the investigation.”

About 10 months after the killing, police received two anonymous answerphone messages from a male caller that seemed significant. Investigators said at the time it was unlikely the calls were hoaxes and the tone and content suggested the caller believed the information was of importance.

Despite an appeal, the caller never came forward or tried to contact police again.

Potential witnesses are urged to contact Thames Valley police on 101 quoting the Janet Brown 1995 murder, or call Crimestoppers anonymously on 0800 555 111.