GARDAI are investigating a chilling Christmas card death threat sent by jealous gangster 'King Ratt' to his ex-girlfriend's new love.
Prison authorities have also launched an enquiry after the feared criminal threatened the life of an innocent member of the public from behind bars.
The jailed gangster, who heads a Crumlin criminal gang, is said to be livid after his girlfriend of 12 years informed him their relationship was over.
She visited the mobster in prison four weeks ago to tell him she wanted to split and the outraged gangster reportedly attempted to assault her before he was restrained by a number of prison officers and placed in solitary confinement.
The pair have a young child together.
Within days of the visit, gardai received intelligence that King Ratt wanted his ex-girlfriend's new lover dead and was prepared to pay a hefty sum to make it happen.
It is understood that the target of the threat has received advice from detectives to improve his personal security.
It is understood that King Ratt feels his pride and reputation have been tarnished by the affair and he wants revenge.
The Christmas card was carefully worded as each letter sent from the prison where the gangster is housed is checked to ensure that no threats or attempts to coordinate crime on the outside are made,
The card read: "Dear XXX. Hope all is good with you and you have a Happy Christmas. Maybe the New Year might bring you something new. Enjoy it. From your friend."
According to sources, detectives will interview King Ratt in the coming days over the alleged threats.
Sixteen people have died in the decade long Crumlin-Drimnagh feud, with the average age of the victims being just 23.
King Ratt is believed to have been responsible for coordinating a number of murders from behind bars.
He is regarded by gardai as one of the most violent and dangerous criminals in the underworld, with along history of mindless violence and no respect for human life.
King Ratt has also carried out a number of vicious knife and gun attacks on other victims but was never charged with these because people were simply too scared.
While at large, he was regarded as a heavy drinker and cocaine abuser.
King Ratt has survived a number of attempts on his life organised by Crumlin gang rival Fat Freddie Thompson.
Since his incarceration, the King Ratt gang in south Dublin has been eclipsed by the drug trafficking activity of Thompson's mob.