The jury was also told that he had been returned to duty in a frontline unit of the Royal Ulster Constabulary after breaking both ankles in what appeared to be an attempt at suicide.
The jury found that Allen Moore, 24, killed himself with a shotgun after first shooting dead three men at a Sinn Fein office in February 1992. The coroner, John Leckey, called for stricter controls over licensed firearms at the conclusion of the longest inquest held in Northern Ireland.
He described Moore as 'a time bomb waiting to explode'. A consultant psychiatrist said there had been key errors of judgement in the supervision of Moore, who had suffered from a combination of depression, alcohol abuse and stress.
A statement from the families of the three men he killed said that if Moore was a very sick man, the RUC should have been aware of it and taken action. Sinn Fein said that the inquest system was inadequate and left many questions unanswered.
Moore had been detained the night before the shootings after he fired six shots over the grave of a colleague. His police-issue weapon was taken from him, and he was found to be drunk.
A GP who examined him believed he was suffering from grief and depression but had not exhibited signs of psychiatric illness. He spent the night at a colleague's home and agreed to turn up for a medical examination the following morning.
However, during the night he telephoned another policeman and said he was going to shoot republican suspects in Armagh, asking: 'Am I scaring you yet?' Instead of reporting for the medical examination he collected his car and picked up his legally held pump-action shotgun.
He talked his way through two RUC vehicle checkpoints and reported to his police station. But after a sergeant asked him where his shotgun was he left the room on the pretext of making a telephone call and drove away at speed.
He went into the Sinn Fein press office on the Falls Road, Belfast, posing as a journalist, and opened fire. He then drove to an isolated spot and shot himself.
The inquest was told that he had damaged his legs by jumping off a wall in what one witness said she believed was a suicide attempt. He was sent to a rehabilitation centre in Harrogate, where he bought a quantity of fireworks.
After his death, police found gunpowder from fireworks, together with other bomb- making components in a locked drawer at his parents' house. A forensic scientist testified that three similar devices had been used in attacks in different parts of Northern Ireland.