The family of a man who killed himself in custody hours after appearing in court charged with rape is furious he was left unsupervised by prison officers.

Mathan Vadivelalagan, of Gorringe Park Avenue, Mitcham, was found unconscious in his cell at Wandsworth Prison by a member of staff at 9.40pm on Thursday, June 12.

Paramedics rushed the 20-year-old to St George's Hospital, Tooting, where he was pronounced dead.

Bereaved father, Vadivelalagan Vaitianathan said: "Whatever he may have done that's a legal issue but the fact is the insecurity of the prison and how he could have made a decision within three hours to hang himself.

"Within four to five hours of him to make that decision, what are the security people doing?"

Mr Vadivelalagan, a Sri Lankan national, had lived in London since December 2012, when he moved to the UK from Tamil Nadu, India, to join his father, a builder, his mother, and four of his brothers.

His father said he had been working at a Mitcham bakery and Wandsworth Tesco to save enough money to study aeronautics engineering at Brunel University.

Mr Vaitianathan said his son had made new friends in the past six months and would take his motorbike to Colliers Wood parkland to meet friends in his spare time and on Saturday nights.

On Wednesday morning, June 11, his parents were shocked when police arrived on their doorstep and arrested their son for rape and assault occasioning actual bodily harm on a woman in her twenties.

Distraught mother Thavarani Vadivelalagan said she last heard from her son on Wednesday evening when he told her he was not guilty of the assault.

She was sleeping in his bed on Thursday night when police arrived to inform the family of his death.

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In a unsigned, poorly-worded letter the family says was given to them by prison officers, they were informed: "Mathan offered a segregation cell due to his offence and age, initially he refused and then with persuasion he accepted to share cell with some his age.

"As there was no-one his age, he had to be put in cell by himself due to safety."

The letter, which a Ministry of Justice spokesman denied was written by prison officers, said he was given food and taken to his cell at 7.30pm, later to be found injured by an officer during their regular check at 9.40pm.

A spokesman for HMP Wandsworth said: "As with all deaths in custody, the Independent Prisons and Probation Ombudsman will conduct an investigation."