A post-mortem revealed Daniel probably died of hypothermia

Daniel Heard, 26, disappeared from the Cedars Mental Health Unit in Exeter in February. His body was found several days later near Cullompton.

Mr Heard from Tiverton, was diagnosed as schizophrenic at 17.

The investigation of Devon Partnership Trust will look into the care received by Mr Heard.

Police role

Daniel's mother, Lynda Kelly, says she welcomes the news that an external review of his death is to be conducted.

The Independent Police Complaints Commission (IPCC) is also investigating the role played by Devon and Cornwall Police played in the search for Daniel.

Mr Heard was an in-patient at the Cedars mental health unit in Exeter when he slipped out on 24 February.

The hospital's missing patient's procedure was activated but it was several days before his body was found by a walker the following Sunday beside the River Culm. It is thought he probably died from hypothermia.

Daniel was not supposed to leave the Cedars unit without an escort and Lynda Kelly criticised the care her son had received and the fact that he had left the unit without being stopped.

Mrs Kelly has also questioned the speed with which police organised a search for her son after he was apparently spotted in Exeter.