Devon and Cornwall police are being investigated for their handling of the disappearance of a mentally ill man, who subsequently died.
Daniel was wearing a T-shirt when he disappeared in February
Daniel Heard, 26, from Tiverton, was diagnosed as schizophrenic at 17.
Daniel's mother Linda Kelly questioned the speed with which police organised a search for her son after he was apparently spotted in Exeter.
The Independent Police Complaints Commission (IPCC) has called in Dorset police to investigate.
Ms Kelly said: "The chance to find him was there with a 100% positive sighting.
"If only they had got up a helicopter or got out a tracker dog within the hour, I am sure he would have been found.
"I thought the police would see that as obvious and would pull out all stops to find him.
"Later that night, I just felt he was dead. It slowly dawned on me there wasn't anything effective being done at all.
"It does need to be looked at. Something went horribly wrong. I can't make sense of it."
When Daniel Heard disappeared on 24 February, it was snowing, but Daniel was dressed in a T-shirt.
His body was found by a walker the following Sunday beside the River Culm.
A post-mortem examination revealed hypothermia was the probable cause of death.
The IPCC has now begun an investigation with Dorset Police acting under the commission's supervision.