Revealed: How corrupt Yorkshire police gave murder case witness sex and drugs

Supergrass and convicted robber Karl Chapman had sex with a policewoman, socialised at officers’ homes and visited pubs while in custody as West Yorkshire Police sought to secure his continued co-operation.

The force also ignored a number of violent crimes allegedly committed by Chapman, including the brutal rape of his cellmate and the vicious stabbing of a fellow prisoner with broken glass bound with twine.

Chapman received special treatment because he was the main prosecution witness in the case of Paul Maxwell, who last month admitted murdering 85-year-old Joe Smales in Wakefield in 1996.

Maxwell and his brother, Daniel Mansell, were originally found guilty of the attack after a Leeds Crown Court trial in 1998, but the convictions were quashed by the Court of Appeal in 2009 on the grounds they had been “procured by gross prosecutorial misconduct”.

Five Supreme Court judges ruled by a majority of three to two last year that Maxwell should face a retrial. More than £3 million of taxpayers’ money had been spent on the case by the time he finally admitted his guilt, for which he received a 17-and-a-half-year jail term.

The Supreme Court judgment, published yesterday, reveals for the first time the “variety of wholly inappropriate benefits” bestowed on Chapman by West Yorkshire officers.

One judge, Lord Brown, who took the view that Maxwell should not have been retried, found that a large number of officers, including “several of very high rank”, were engaged in a “prolonged, persistent and pervasive conspiracy to pervert the course of justice”.

Officers colluded in Chapman’s perjury during the trial, the judge found, intending him to lie throughout his evidence about how he had been treated.

They ensured Chapman’s police custody records presented a “false picture of the facts”, even forging one to conceal the truth, and they lied to the Crown Prosecution Service (CPS) after the trial.

Lord Brown stated: “To describe police misconduct on this scale merely as shocking and disgraceful is to understate the gravity of its impact on the prosecution process.

“It is hard to imagine a worse case of sustained prosecutorial dishonesty designed to secure and hold a conviction at all costs.”

None of the officers involved in the case have been prosecuted or disciplined. All have since left the police service and at least one is understood to be living abroad.

The full extent of the corruption was uncovered by a North Yorkshire Police investigation on behalf of the Criminal Cases Review Commission, which probes potential miscarriages of justice.

It is understood that some West Yorkshire officers refused to co-operate with the inquiry.

Investigators found that Chapman regularly had sex with a woman police constable but he cheated on her when her colleagues took him to a brothel – a trip described on the custody record as an outing to “assist in the locations of crime”.

Chapman wrote to the woman officer, apologising: “I was drunk and stoned on weed, they paraded a dozen beautiful women in front of me and said take your pick.”

It is alleged that Chapman later assaulted the officer after they broke up, but the case was one of several against him which were not prosecuted.

Last night Maxwell’s solicitor Mark Foley said he was stunned by the “incredible scale of the malpractice exposed”.

Deputy Chief Constable David Crompton said: “In relation to the original investigation back in 1996, the methods used to deal with the main witness were wholly unacceptable and cannot be condoned in any way whatsoever.”

Following the North Yorkshire Police inquiry “the CPS concluded there were no criminal offences committed by any officer.”

Mr Crompton continued: “Since the original investigation was carried out 16 years ago there has been a complete root-and-branch overhaul of procedures to safeguard against such failings and to prevent them from ever happening again.”