THE father of a man shot dead in a County Durham field has put up a £20,000 reward for anybody who gives evidence leading to the conviction of his son's killers.

The body of 23-year-old Mark Corley was found in a ditch at a farm near Bolam, near Darlington, in December 2000 - five months after he went missing.

His father, Tony, originally from Lincolnshire, has fought for 15 years to keep the case in the public eye.

Mr Corley, 63, of Leicestershire, has written a book called More Questions Than Answers? which is available on Amazon Kindle.

Mr Corley said: “Nearly 16 years have passed since the case collapsed leaving me very frustrated, angry and bitter. I know there are people out there who know the truth.

"Don’t be afraid to come forward and tell the truth. Sixteen years is a long time and people change, hence the reason a close colleague has offered £20,000 reward for the successful conviction of my son’s killers.

“If for one moment I didn’t believe there wasn’t any evidence out there I wouldn’t let this reward go ahead. Does someone know you are out there?

"Someone just go to your local police station, clear yourself if you have good clear evidence against Mark Corley’s killers to gain a successful conviction and £20,000 will be yours.”

Nobody has ever been convicted of the killing.

In 2001, a judge threw out the case against five suspects after it was discovered police had illegally bugged their conversations with solicitors.