Trevor Walsh had walked free from the Midlands Prison on Thursday, but was shot four times in the head and body at close range on Saturday morning on the streets of Finglas.
A lone gunman was seen escaping by bicycle from the bloody murder scene at Kippure Park, not far from Walsh’s own locality in Valley Park Road.
Detectives were last night not ruling out the possibility that 33-year-old Walsh, who had strong connections to criminals in Finglas, knew his killer. Walsh had finished a three-year sentence for firearms offences, having been released early.
“Someone had a grudge against him because he didn’t last very long,” said an investigation source.
Walsh had close to 50 convictions and was associated with leading Dublin criminals who have also been killed in recent years. These include John Daly, the convicted robber who telephoned RTÉ’s Liveline from his cell and was later shot dead after his release.
“He [Walsh] had a lot of debts and a lot of enemies,” added the source.
A report that Walsh was killed because he had become an informer for gardaí was not confirmed.
The gun murder was the second within 10 hours in Dublin.
Drug dealer Anthony Foster was shot dead at close range after he stepped out of his top-floor flat at Cromcastle Court, in Kilmore, north Dublin, at about 1.45pm on Friday.
The 34-year-old father was on his way with his partner to a nearby creche to pick up their children.
A recovering heroin addict, Foster had been recently released from jail after serving a six-year term for drug trafficking.
He had been working with addicts at a drugs agency, Merchants Quay, in 2000 when he was caught with £30,000 worth of cannabis.
Several links to his shooting are being considered, including a row with another inmate when he was in prison as well any disagreements with the gang that Foster was dealing for.
Gardaí were not linking the shootings of the gangland figures over the weekend. Senior officers say they are keeping an open mind on both investigations.