Allegations have emerged of the neglect of a mentally disabled Cornish man following claims of abuse of patients in the county.
Budock Hospital, the centre of the commission's investigation
Health watchdog the Healthcare Commission has sent in an expert team to improve services as part of an investigation into claims of abuse.
It said the unusual move was prompted by "significant failings" at the Cornwall Partnership NHS Trust (CPT).
Some concerns relate to Budock Hospital near Falmouth.
Carol Blakey from Truro removed her physically and mentally disabled son Ryan, 25, on two occasions from Budock, a treatment centre for 14 in-patients with conditions like autism, Asperger's and Down's syndrome.
Ryan was under 24-hour supervision when his parents were called to the hospital.
Mrs Blakey said: "We had a phone call saying there had been an accident. He was covered in blood on a sofa.
"We don't know what had happened to him, but the top of a finger had been sliced and the nerves were damaged."
The family had no reason to suspect that the injuries had been caused by anything other than an accident so they let social services re-admit Ryan two years later.
But when they went to visit him they were horrified by what they found.
Mrs Blakey said: "Ryan was walking up and down in a state of seizure. His eyes were zombified and he was just walking up and down ripping his fingers.
"He was filthy dirty. He had dried food all over his face and in his fingers and dried blood."
When Ryan got home they undressed him for a bath.
Mrs Blakey said: "His nails were curled under. They had not been cut. His teeth were yellow and his hands were so sore it took my husband and I an hour to get him into the bathroom."
The Healthcare Commission launched its investigation in June following claims of abuse and six staff at Budock Hospital were suspended.
Four staff have been sacked and two are still suspended.
'Matter of urgency'
The commission said on Tuesday that it was taking the unusual step of sending in an expert team before completing its enquiries in order to protect people with learning disabilities.
Criminal proceedings could be brought in six cases of alleged abuse which have been referred to the Cornwall Adult Protection Committee, a multi-agency body including social services and the police.
CPT spokesman Tony Gardner said: "There have been issues and we have taken action that we see fit.
"Clearly the Healthcare Commission have had an investigation and has taken the view that things need to happen as a matter of urgency.
"We welcome that expertise to work with us to find solutions to the problems that have arisen."