This dangerous villain was the second man to become a "supergrass" but as has been shown, many of these men can never turn their backs on crime, despite their vows to go on the straight and narrow. Born in 1947, he became involved in crime at an early age, but according to his memoirs, his move into big time violence occurred in 1964 when he claimed that an associate was responsible for having some other villains break both of his wrists with a pickaxe handle. When healed, he found the guy, and walked him to the edge of the Thames with a sawn off shotgun, intending to blow him away, but a friend persuaded him not to. Instead he picked up a broken bottle and used that on him, then knocked him into the river.
He graduated into armed robberies and burglaries, violence on demand - he claims to have been hired to shoot people in the legs. Nothing was beyond him. Beatings to the head and kneecaps with a hammer, were all in a days work. But after a raid by Police over an armed robbery, whilst in a prison cell, he decided that he would confess all. His girlfriend had been threatened, and he was attacked by other members of the gang, threatening to gouge out his eyes. He claims (naturally) that the others were cutting deals with Police in order to save themselves so he decided to get in big time. He spoke to Chief Superintendent Jack Slipper and told of murders, burglaries, armed robberies, violence, hijackings and anything else he could think of. Jack Slipper said in his memoirs that O`Mahoney said he was sick of crime and wanted to get out, something Slipper was not very impressed with. He was kept in what became known as the "Grasshouse" - Chiswick Police Station, enjoying games snooker, visits from his girlfriend, fishing and golf trips with his guards.
He has supposed to have given up more than 200 villains during his confessions, and admitted over 100 crimes, involving more than 15 armed robberies, and dozens of burglaries. He then received what was to become the supergrass tariff of just five years. Contracts were put out on him, and one former villain claimed that he missed being killed by minutes. He was spotted in a place in West London, and when a car full of villains arrived, he had already left. He received a bullet through the post with the message "The next one comes through your fucking head!" But as repentant villains show, he appeared at the Old Bailey in 1993 charged with robbery. He claimed that the Police used him to carry it out in order to fit up another villain. He also claimed the Police wanted to kill him because he may have been ready to expose widespread corruption. His performance in the witness box earned him an acquittal. He was reported to have died in 2003, up in Northumberland, following a heart attack. No doubt many of his former accomplices toasted his passing.