A father whose son was murdered eight years ago fears he will never see the killer brought to justice.

Mark Corley, 23, was shot in the head and his body buried in remote farmland in north east England, on an unknown date in 2000.

Five people were charged in connection with Mark's death, but the trial collapsed when it emerged police had unlawfully bugged the suspects.

Nobody has since been arrested for the killing, although police insist the investigation is "regularly reviewed".

Mark's father, Tony Corley, of Asfordby, near Melton, now plans to write a book about the family's ordeal.

The 55-year-old admitted, however, "the book will be more questions than answers".

Mark, who grew up in Eyres Monsell, Leicester, fell in with a "bad crowd" when he moved to Grantham, Mr Corley said.

He said: "Our family is left with all these questions, which I don't think will ever be answered now. I don't think we'll ever get justice for Mark.

"He was a good boy, but he was easily led and got involved with a bad crowd.

"I have heard different stories about what happened to him, but I can't take them as gospel. I want to write a book about all of this to get everything off my chest, and to make sure Mark isn't forgotten."

Mark grew up in Eyres Monsell, before moving to Grantham, in Lincolnshire, with his mother, Eileen.

He was a former pupil of Leicester's Mary Linwood School, and often returned to the city to visit his father and friends.

In 2003, when it emerged Lincolnshire detectives could face prosecution for their conduct during the investigation, Mrs Corley said: "I live with the hope of getting justice for my son's death every day of my life – but I don't think I'll ever get it now."

Rose Dixon, of Support After Murder and Manslaughter, of which Mr Corley is a member, said: "Families struggle when they lose a loved one.

"But there is often some satisfaction when they get the answers to their questions during a trial.

"Not having those answers is a real burden on families."

The investigation into Mark's death was led by Lincolnshire police. Detectives arrested five suspects and secretly taped their private conversations with the solicitors.

A judge halted the trial in January 2002, saying the police had committed "flagrant breaches of the law".

A spokesman for Lincolnshire police said unsolved cases were reviewed regularly and the force would investigate any new evidence.

The force has apologised to the Corley family for the conduct which caused the trial to be abandoned. A number of detectives were disciplined, not prosecuted, the spokesman said.