MERSEYSIDE Police has referred itself to the Independent Police Complaints Commission, after a serial sex attacker it was meant to be monitoring raped and murdered a 17-year-old girl.

The force took nine months to issue a national wanted alert after realising Peter Chapman had vanished from his Kirkby home early last year.

Just a month later he kidnapped, raped and murdered Ashleigh Hall, in County Durham.

He posed as a teenage boy on Facebook to trick Ashleigh into meeting him before killing her and dumping her body in a farmer’s field.

He had strangled the childcare student and dumped her near a lovers’ lane. Police carried out an internal review of their actions when Chapman was arrested, but further scrutiny will now follow.

Speaking about the IPCC investigation, a spokesman for the force said: “Merseyside Police can confirm that an internal review was carried out following the arrest of Peter Chapman in October last year.

“Following the review, a number of procedural improvements were identified and subsequently implemented.

“However, in view of the public interest and concerns raised following the conviction of Peter Chapman and to ensure complete transparency in terms of this particular matter, the force has referred it to the Independent Police Complaints Commission.”

The IPCC’s job is to ensure complaints against the police are dealt with effectively.

Chapman, sentenced to a minimum of 35 years in jail, was last seen by police at his home on August 29, 2008.

An officer spoke to him on the telephone on September 24 that year.

Merseyside Police said that, up to this point, he “had remained fully compliant with his registration requirements” that were forced on him by being on the sex offenders’ register.

Police visited his home on January 6, 2009, to discuss a traffic matter, but he was not in.

Different officers were supposed to visit him a month later, in line with his sex parole checks, but again he was not in.

The force maintains that officers then worked to establish his whereabouts locally.

But it was not until September last year – just a month before he murdered Ashleigh – that the police issued the nationwide wanted alert.

The force referred its handling and review of the Chapman case to the IPCC as Home Secretary Alan Johnson demanded answers.

The minister called on the police to “respond” and said lessons “needed to be learned” following Ashleigh’s murder.