AN MP's campaign to free the self-confessed murderer of a former Newcastle United footballer has been attacked by the detective who investigated the case.

Labour's John McDonnell has asked House of Commons colleagues to sign an Early Day Motion claiming Irish jockey Christy McGrath had been "unjustly sentenced" for last year's killing of Gary Walton, from Coundon, County Durham.

The motion demands an immediate referral to the Court of Appeal and claims a "lack of forensic evidence" in the case.

Yesterday, there was only one signature on the motion - that of Mr McDonnell, who represents the Middlesex constituency of Hayes and Harlington.

And the detective who led the murder inquiry hit back at the MP's assertions that McGrath was arrested on a "trumped up charge" and that the investigation had been flawed.

Detective Superintendent Tom Ryan said: "I refute completely that there was no proper police investigation. It is a slur on the police and it is also a slur on the people of Coundon who provided us with a lot of information.

"The MP was ignorant of the full facts of the case and was speaking from a position of weakness."

McGrath had been due to stand trial in January, but changed his plea to guilty at the eleventh hour after speaking with his mother, Ann. He was given a mandatory life sentence.

The court was played tapes of mobile telephone calls in which he pleaded with friends to pick him up, and his footwear and phone were covered with Mr Walton's blood.

Det Supt Ryan said the case against McGrath had been overwhelming, adding: "We had evidence from Home Office pathologists, from the forensic science service and voice analysts. He admitted it was his voice on the telephone.

"The allegation that somebody else could have killed Mr Walton was also covered in the fullest detail."

McGrath's brother, Larry, denied the campaign to free his brother was aimed at hurting Mr Walton's family.

He said: "We know what they are going through and we understand how they are feeling. My parents have lost a son as well and I have lost a brother.

"But at the end of the day, my brother is still alive even though he is not with us, and for his sake we have to fight for the truth to come out."