Longreach House cost �6.5m to build

The investigations are into three separate deaths at Longreach House at Camborne Redruth Community Hospital between March and June this year.

Cornwall Partnership Trust, which runs the 67-bed unit, confirmed none of the deaths were being treated as suicide.

Dr Terry McClatchey said they did not know how the patients died, which gave them "cause for concern".

There were no suspicious circumstances in terms of injuries ... but we don't have a formal cause of death Dr Terry McClatchey

Longreach House opened in August 2003 at a cost of �6.5m. It was designed to replace three other mental health units in the county.

In March, a 44-year-old female patient died whilst taking a shower. Henry Gibb, 22, was found dead in his bed by staff in June.

A day after Mr Gibb was found dead, a 65-year-old woman collapsed and died in one of the communal areas.

Mr Gibb was being treated for depression and anxiety. Two months on, his mother, Mary Gibb, said she still did not know why her son died.

She said: "He went in on a Tuesday evening.

"I went in to see him on the Thursday and he seemed bright and very together compared to how he had been.

"So, on the Friday, when doctors came around to tell me he had been found dead in his bed, I was just devastated."

She said her case had now been taken up by her local MP.

The Cornwall Partnership Trust said that none of the deaths were being treated as suicide and all were being investigated.

The trust's Dr Terry McClatchey: "We have deaths where we don't have an official cause.

"There were no suspicious circumstances in terms of injuries, or that one patient might have injured another.

"But we don't have a formal cause of death for each of these three cases, and that is a cause of concern."

Inquests into all the three deaths are likely to be held together, but are not expected to take place until next year.