MYSTERY still surrounds the death of a wealthy businessman who was subjected to a terrifying attack outside his West Yorkshire home.

Post-mortem tests proved inconclusive on John Luper, 57, who was attacked by a gang of men as he walked his dog.

The thugs had already broken into his luxury Leeds home and tied up his wife, daughter and another woman.

But police have so far been unable to determine what caused Mr Luper's death.

Mr Luper was a close friend of former Huddersfield Town chairman David Taylor.

He was a prominent member of the Jewish community and also a Freemason in West Yorkshire.

He made his fortune in the family clothing business in Leeds many years ago but had recently been involved in several other businesses, including serving as a non-executive director of a football and entertainment agency which deals with stars including Arsenal's Thierry Henry and Denis Bergkamp.

Mr Luper was attacked at 11.30pm on Monday by three or four men as he walked his dog near his £800,000 house in the affluent Alwoodley area of Leeds.

Police said Mr Luper was dragged back to his detached home, where the intruders appeared to have entered the property and tied up his wife, Iyican, his daughter and another woman.

They were threatened while the raiders searched the property before fleeing. It is not yet known if anything was taken.

Police said the women managed to break free and raise the alarm.

Mr Luper was found collapsed in a room close to the kitchen by his family.

Paramedics tried to resuscitate him but he was pronounced dead at the scene.

Detectives are treating the death as suspicious and it is thought robbery was the motive for the "horrific and despicable" attack.

Mr Taylor said he was shocked and saddened by the news.

He said: "John was a very good friend. He had a heart of gold."