THE bullets used in the botched John Gilligan hit were stolen from German police 10 years ago.
Four bullets were extracted from the body of the former crime boss and forensically examined by gardai.
Officers sourced them to a cache of tens of thousands stolen from the German Federal Police a decade ago.
The theft was discovered during an internal munitions audit by German authorities.
Subsequently, some of the ammunition found its way to Ireland's criminal gangs and was used in the gun attack on Gilligan on March 1.
The convicted drug-trafficker remains in James Connolly Hospital in Blanchardstown where he has been treated for a broken leg and damaged bowel.
Sources have also confirmed a Czech-made CZ 75 semi-automatic pistol was used to shoot him at his brother's home in Clondalkin.
The same type of handgun, also containing stolen German police ammunition, was recovered last December after a hit team dumped the weapon following another failed attempt to murder Gilligan (62).
Gardai have seized a number of the Czech-made pistols in recent years, but this is the first time they have found one loaded with this ammunition.
A source said: "Forensic tests show the ammo used to shoot Gilligan was also found in the pistol recovered following the abortive murder attempt.
"It has been confirmed that the bullets were from a large cache of ammunition identified as stolen from the German Federal Police 10 years ago.
"It has filtered out to the underworld and has found its way to Ireland, possibly as part of a drug consignment."
Gardai say that the discovery proves the same gang was responsible for both attempts on Gilligan's life.
Detectives remain fearful that the gunmen will again go after the notorious criminal when he is released from hospital during the next few weeks.
Ironically, it was Gilligan who first imported huge amounts of Eastern European guns and ammunition into the country when he moved into the drug trade in the early 1990s.
A source said the once-powerful crime boss had crossed the wrong people this time.
"He has upset a gang who have armed themselves with a cache of weapons from Eastern Europe, and they have decided that they want him out of the way," the source added.
Earlier this week, the mobster was moved from his normal hospital bed to a private one after he complained.
Gilligan, who is being protected by armed officers, had said to doctors that he had no privacy in the public ward where he was being treated.
It is understood that he is also afraid of being photographed by the media.
Last week, a photographer who had snapped Gilligan while he was being moved for an X-ray deleted the picture after he was confronted by Gilligan's bodyguards.
Security sources say the once-feared gang boss is sitting up in his hospital bed and is resting his broken leg on a stool.
He has stitching over a grazed eye and has been doing physiotherapy.