Christmas brought back unbearable memories for Deveen Clarke, for last week marked the anniversary of her husband Mario’s shooting – a killing which remains unsolved to this day.

She was a trainee nurse who had married her soldier sweetheart just months earlier. The couple had left their native Jamaica to settle in Britain and were living in London. Mario was on two weeks’ leave from the Army and had spent Boxing Day 2002 visiting friends and family.

The couple were going to go out that evening and the 25-year-old soldier was sitting in his car outside their home in Hackney, east London, chatting to his brother and cousin. A man approached the car, shot him once in the heart through the window, and vanished. Despite a £10,000 reward offered by police, the killer was never caught.

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Mario had been posted to Deepcut barracks in Camberley a few months earlier and was halfway through a training course. He had complained to his wife of problems he was having there. More disturbingly, he said he did not believe that the deaths of four trainee soldiers, found shot at Deepcut between 1995 and 2002 amid allegations of a culture of bullying, were suicides.

Within months of Mario’s death, Home Office officials began attempts to deport his widow to Jamaica. She was later refused a visa to return for the inquest into her husband’s murder, which was held in 2004, but still hopes that one day she will find out who killed her husband, and why.

A recent application to the Attorney General by the human rights charity Liberty for the inquest into the death of one of the Deepcut recruits to be reopened has reawakened painful memories for her. In her first interview in a decade, Mrs Clarke told The Independent that Mario had called her from Deepcut earlier that year and confided in her about his concerns over the deaths at the barracks: “He was saying that he knew they didn’t commit suicide. I asked how did he know, but he just said that when people say that they committed suicide that’s not the case. He believed that the Army killed them.”

The police ruled out any connection to Deepcut. “They said he was in the wrong place at the wrong time,” she added. “They were saying that it was a black-on-black shooting. But we were all saying, ‘There were three people in the car. If it was a black-on-black shooting, they would shoot everyone, not just Mario.’ I don’t think they investigated thoroughly to find out if there was some connection.”

She continued: “I think he was assassinated, I think he was executed. The car window was wound up and the person that killed my husband knew how to use a gun. Maybe my husband had known something and they didn’t want him to disclose it.”

She is convinced she was deported for speaking out: “I think the Government refused my stay in the UK because I joined with the other families who were campaigning against the Deepcut shootings.”

A spokesperson for the Metropolitan Police said: “We retain an open mind regarding motive. We have no evidence this murder is linked to other events at Deepcut,” adding that “mistaken identity” was one line of inquiry. The Ministry of Defence was unable to comment on Sunday.