Rolling up his grey sweatshirt sleeve, Sean Hodgson looked ashamed as he revealed a needle mark and a bruise in the ashen skin of his left arm.

After nearly 30 years in prison for a murder he did not commit, the frail man, who has aged way beyond his 58 years, stammered as he explained why a drug dealer gave him free heroin. “It’s because of the compensation I am going to get,” he said. Mr Hodgson, a drug and drink addict before his incarceration, is being approached by “gold diggers”, who know that he stands to receive up to £1 million in compensation for wrongful imprisonment.

With both his legs rocking relentlessly from side to side, he said that the dealer wanted to get him hooked again in an attempt to steal some of the cash, either by becoming his pusher or by gaining influence over him.

Mr Hodgson, who was released from jail two months ago after DNA tests proved he did not kill Teresa De Simone in 1979, is one of the longest-serving victims of a miscarriage of justice in British legal history. Only now can it be revealed that Mr Hodgson, who suffers from schizophrenia and depression, has been deemed so vulnerable and emotionally fragile that the money is to be protected by law.

Jacqueline Almond, a solicitor, has been appointed by the Court of Protection as a deputy to ensure that the cash is spent in his best interests. Interim compensation of about £250,000 has already been paid into the fund.

“It was necessary to protect the funds for Sean’s own benefit because he has been classed as a vulnerable individual by the court,” Ms Almond said yesterday. The decision was made after London’s criminal underbelly identified him as a potentially lucrative target. He has received letters from women proposing marriage and, he claims, recently fallen out with someone close to him when he explained that he could not give away any of his money.

But on Wednesday his past life of drug and alcohol abuse caught up with him. As he roamed the streets near his lodgings in Notting Hill, West London, he was approached by a drug dealer, a man he had known in the 1970s.

In what Mr Hodgson described as a “moment of madness”, he went to the man’s flat, slumped on to a sofa and injected heroin into his arm. Weighing a mere 9st 9lb — a stark contrast to the 13st he weighed before his arrest — Mr Hodgson said that the drug had an immediate and alarming effect.

“I felt sick. I started hallucinating and hearing voices,” he said. At dawn, he stumbled out on to the deserted streets and made his way to his Mayfair lawyers, a team he had come to trust after they fought successfully for his conviction to be quashed.

Julian Young, his solicitor, admitted being shocked when he saw his client.

“Sean was not well. He was complaining of hearing voices, slurring his words and was confused and sweating badly. It was obvious he had taken drugs and had not been taking his prescribed medication. We took swift action. An ambulance was called and he was taken to Chelsea and Westminster Hospital for treatment.” Mr Hodgson interrupted: “They want me back on the drug scene. The dealer knew I was going to come into money. I don’t want to go back to drugs. I told them to f*** off and left.”

It was perhaps in part his drug and drink abuse in the Seventies that led to his confession. When his common blood type matched traces at the murder scene, that confession appeared watertight. As quickly as he had given it, Mr Hodgson, who was in the habit of making false confessions as a way of seeking attention, withdrew his testimony and pleaded not guilty. But he was jailed for life.

In 1998 the Forensic Science Service disclosed that it did not have the exhibits from the trial. In 2008 Mr Young and his partner, Judy Ramjeet, became involved and, after dogged research, traced the samples. DNA from swabs from the victim’s body proved that the building site odd-job man and petty criminal did not rape and murder her. The failure of authorities to find those swabs ten years earlier could push compensation up to £1 million.

As he emerged free from the High Court in March, Mr Hodgson encountered a different world: faster cars, ticketless public transport, e-mails instead of letters and mobile phones. But because he had refused to admit guilt and his release was unexpected, he had not been given advice on how to cope. He was handed a prison discharge payment of £46 and had to rely on his siblings in the North East before returning to London, where the psychiatric support he so desperately needs is readily available.

“It’s all changed,” Mr Hodgson continued. “The whole world is faster and noisier. There are so many foreigners. It’s confusing.” For Mr Young, his client’s case is yet more proof that a system needs to be introduced to help innocent lifers released from jail to adjust to freedom.

“When Sean was freed, it was patently obvious that he was unable to deal with everyday things, let alone his finances or a substantial sum of money. My fear was that people would try to gain access to his compensation, a fear now borne out.

“In my opinion, the support available through the Miscarriages of Justice Unit is as good as their meagre resources allow. For the very few people like Sean, who are released because they’re innocent, the support should be as good as that for the guilty when they’re freed, if not better.”

Mark Field, a Conservative MP, and Hilary Armstrong, a former Labour minister, are trying to ensure that Mr Hodgson gets the help he needs.

“It’s payback time,” Mr Field said. “It is unacceptable that, given the injustice this vulnerable man has suffered, he still has not been given money to help him since his release. It’s as if he’s dropped out of the system, as he roams the streets of London.”

A few days before agreeing to this interview, Mr Hodgson was stooped over his parents’ grave in a windswept cemetery in the Wear Valley, Co Durham. He moved to the area aged 4 with his family, who are from Ireland.

“It was a promise I made when they died while I was still in jail,” he said. “I told them, ‘I love you Mum, Dad’. And then I said that I was innocent all along. They both knew that. They died broken-hearted.”

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