Police have appealed for information to crack the unsolved murder of a millionaire Jewish businessman, eight years after his death.

West Yorkshire Police believe local criminals have information about who killed John Luper at his mansion in the heart of the Leeds Jewish community during a brutal raid in February 2004.

The 57-year-old, whose consultancy represented sports figures such as Thierry Henry and Rio Ferdinand, was dragged back into his home as he walked his dog, and died while being manhandled by masked raiders. His family were tied up, and the gang escaped, with £100,000 in cash and jewellery.

On the anniversary of Mr Luper's death, his family broke an eight-year silence over the devastating effect of the killing, to help renew a police investigation.

Last week, at Leeds United Hebrew Congregation, they marked the shared yarzheit of both John and his mother Olga, who died on the same Hebrew date, five years after John's murder. Mr Luper was a well-known donor to Jewish charities, including donating a room to UHC Synagogue.

His brother Toby Luper said the family "still suffer, if not every day, from the trauma. You can't imagine being tied up, then to find your husband and father murdered after you free yourself - it must have been horrific".

Toby Luper received a call from John's daughter Liza-Rose, then 20, and wife, Lycian, minutes after they untied themselves and called the police.

They found John unconscious with marmalade smeared on his mouth, after the raiders attempted to revive him, believing him to have collapsed from diabetes. The Leeds coroner ruled his death was caused by asphyxiation.

Toby Luper said: "I want the public to come forward with any information that they may have. Just the smallest thing could make all the difference."

Police are now re-examining old evidence using new forensic techniques. They believe locating Mr Luper's rare Cartier watch, one of only four sold in the UK at the time, could lead to fresh lines of inquiry.

Detective Chief Inspector Simon Atkinson promised the strictest confidence to "a number of people out there with more to say. In the eight years that have passed since Mr Luper's death, allegiances change and I would appeal to the criminal fraternity to come forward and help us bring those responsible for this man's death before the courts".