THE mother of the fourth prisoner this month found hanged in Durham's prisons has called for an inquiry.

Father-of-two Jason Mackin was found hanging in his cell in the hospital wing of Durham Prison on Saturday afternoon. The 28-year-old, from Wigan, was serving four years and four months for robbery, assault, issuing threats to kill and affray, following a violent raid on a pub in Wigan.

His mother Christine, who lives in the Lancashire town, said her son was being treated in the hospital wing for depression and anxiety and demanded to know why he had not been on suicide watch.

She said: "There are some very serious questions that need answering: why did Jason die, how was he allowed to die and why is he the third person to die at Durham Prison in such a short time?"

On October 7, remand prisoner Terence Gaskell, also from the Wigan area, was found hanging from a bunk bed at Durham Prison.

On October 2, Beverley Fowler, 32, from Jamaica, was found dead in her cell at the prison's Women's Centre and on the same day Paul Stewart Day, 31, from Essex, died in Frankland Prison. In both incidents, which were unconnected, the inmates were believed to have hanged themselves.

The Prison Reform Trust, a charity dedicated to creating a more humane and effective penal system, said it was becoming increasingly concerned about the pressures on prisoners and staff as prison numbers rise.

Director of the trust Juliet Lyon said: "It's difficult to see how an overcrowded prison can still manage to care for its inmates. It is a tragedy that despite the best efforts of the Safer Custody Group, the number of deaths by suicide has risen this year."

"Over the last year there were 81 deaths for the whole year, as far as I can see we're already over 80 and November and December are often the worst months."

Members of the Mackin family were travelling to Durham on Tuesday to find out more about the incident.

A Prison Service spokesman said as with all deaths in custody, there would be an investigation by the Prison Service. He confirmed Jason Mackin had not been on suicide watch.

He said: "Obviously a judgement is made by experienced prison service staff on each individual case."