Gardai and the PSNI are investigating a possible link between the murder of the Belfast IRA boss, Gerard 'Jock' Davison and a major drugs smuggling gang in Dublin.
The same type of pistol used in the murder was previously used by Eastern European mafia in Dublin, according to garda sources. One of the attacks linked to the type of pistol - which cannot use standard Western 9mm ammunition - was described as one of the most 'professional' assassinations carried out in the State.
It was used in the murder of Stephen 'Dougie' Moran (42) in March last year. Moran was shot because he was acting as 'security' for former gang boss John Gilligan following his release from jail in October 2013.
Moran was driving an armoured BMW X5 car and had bullet-proof windows installed in his home at Earlsfort View in Lucan. His assassin had only a 'window' of a few seconds after Moran pulled up at his home on the evening of March 15 last year. Moran was killed instantly in the attack and no one has been charged.
Gardai believe Moran was shot by professional assassins hired by the major drugs gang, based in Marbella in Spain, which controls much of the illicit trade in cocaine, heroin and other drugs in Ireland. This gang, police on either side of the border now believe, is spreading its trade and influence across the border.
In recent years, the market for heroin and other opiate drugs has been expanding in Northern Ireland as havs the number of local dealers.
Associates of these local dealers, who have now forged closer links with their counterparts in the Republic, were killed by Davison's IRA gang in the past.
The leader of the Spanish-based drugs cartel is known to have also had close associates murdered by the Provisional IRA in the past. One of the theories being investigated by the two police forces is that Davison (47) may have been murdered by professional assassins, possibly from Eastern Europe, by the Dublin mob as a 'favour' to their new partners in Belfast.
The Makarov pistol is widely used in former Soviet Bloc countries but is hardly used at all by criminals or terror groups here as it has a different calibre from Western-manufactured automatic pistols.
The use of the weapon was first detected here in March 2011 when one was used to shoot a Polish businessman as he was leaving his home in south Co Dublin. The man and his teenage son were seriously injured but recovered. It is understood a similar pistol - manufactured in their millions in Soviet countries between 1951 and 1991 - was used in the murder of Lithuanian gangster Gintaras Zelvys (43) in May 2013. Zelvys was engaged in a variety of crimes and was shot outside a second-hand clothes depot.