DETECTIVES revealed today that North Yorkshire's two double murders could be linked - and that every police officer in the country had been briefed about the man they want to question about all four deaths.

Detective Superintendent Javad Ali told a packed press conference in York today that Mark Hobson was "clearly dangerous", and Deputy Chief Constable Roger Baker said: "We want to speak to him about four murders."

Mr Baker added: "Every police officer in the country has been made aware of our inquiry".

Mr Ali said police had a "confirmed sighting" of Hobson in the Wigginton Road area of York at 2am on Sunday, the day frail pensioners James and Joan Britton were found dead in nearby Strensall.

As a result of extensive inquiries, they had a possible sighting of someone of a similar description to Hobson in the Strensall area at about 9.15am the same day. The Brittons were found dead at 11.26am.

He said this and other evidence suggested the murders "could be linked" with the killings of twin sisters Claire and Diane Sanderson at Camblesforth. Their bodies were found at 8am the same day.

Hobson was Claire's boyfriend and they had recently moved to Camblesforth.

Mr Ali said they had not established any previous association between the Brittons and the Sandersons, or anything that had previously connected Hobson to the Strensall area.

Police revealed that there were similarities between the injuries suffered by the victims.

A post-mortem examination on the 27-year-old twins had shown that Diane died through strangulation and also suffered other injuries, while examinations in Claire's case had been unable to establish a cause of death. She had, however, suffered a violent assault.

He said post-mortem examinations of the Brittons had established that Mr Britton, 80, had died as a result of stab wounds and other severe injuries to his body, and Mrs Britton, 82, had also suffered stab wounds, but the initial results of the post-mortem had been unable to establish an exact cause of death. Both were found downstairs at their home.

He said that extensive inquiries had so far proved unable to locate Hobson, 34, and police needed to speak to him as a matter of urgency.

On the Strensall murders, Mr Ali said: "This is a very horrific and cowardly attack against two frail and law-abiding people. We really want to find the person, or persons, responsible for their deaths."

Mr Baker said: "Murders are very rare in North Yorkshire. To have two double murders is unheard of. We are doing everything possible to bring the person, or persons, responsible to justice as quickly and as safely as possible. It is imperative that we find Mark Hobson."

The parents of Claire and Diane were today said to be "inconsolable".

It emerged that the bodies of the 27-year-old twins were found by their traumatised father, George, at a flat in Millfield Drive, Camblesforth.

It is thought the day before she died Diane left her car in Selby overnight while she visited her sister in Camblesforth.

Former Selby shipyard worker Mr Sanderson, along with Diane's boyfriend, took the car to Camblesforth on Sunday, when they made the tragic discovery.

They were seen by neighbours crying on the kerbside.

Diane lived with her parents in a bungalow, in East Cowick, near Selby.

She was assistant manageress at Rosebys curtains and linens' shop, in Selby's Market Cross shopping complex.

A workmate said: "Diane was a lovely, quiet woman. Her parents must be going through hell. To lose one daughter is terrible but to lose two is unimaginable."

Diane and her boyfriend, from Selby, had been together for several months and it was becoming a "serious relationship."

The twins were the only children of Mr and Mrs Sanderson, who are said to be "absolutely devastated".

"You can't imagine what George is going through after finding both his daughters in those terrible circumstances," said the friend. "It's such a tragic waste."

A close friend of Claire said: "She was lovely lass, very down-to-earth, polite and pleasant.

"If a bloke started speaking to Claire, he (Hobson) would get very jealous and she would get it in the neck."

He said Hobson, a divorced father-of-three, was a heavy drinker and a regular at the Blackamoor Head and Cricketers Arms pubs, Selby.

Hobson worked for Onyx, which collected refuse for Selby District Council, but left last month.

At York Crown Court in June, 2002, Hobson, received a two-year probation order and 100 hours of unpaid community work after admitting wounding William Brace with intent to cause grievous bodily harm. The victim needed emergency surgery.

At Selby magistrates in February, Hobson admitted stealing a gold wedding ring and a diamond engagement ring from his sister, pawning them to fuel his alcohol addiction. He was given 50 hours' community service.

Claire had worked at Rigid Containers' factory, Denison Road, Selby.

A small pile of floral bouquets has been left outside the Brittons' house in Strensall today. One was accompanied by a card which read: "Mr and Mrs Britton, I'll miss you so much. Love Caren."

Updated: 13:48 Tuesday, July 20, 2004