The gangland boss suffered a heart attack in Broadmoor at the age of 61 and died in Wexham Park Hospital a couple of days later.
Eleven people have already been questioned and released without charge in connection with this gangland murder.
They have been provided with the type of new identities and false life histories normally reserved for spies and gangland informers.
The murder comes after a lull in the number of gangland shootings and killings in the past few months.
The murders of police officers and Serbian gangland criminals share similar characteristics.
He had no criminal convictions or known gangland connections.
Crime is falling, gangland criminals are on the back foot and more Gardai are on the beat than ever before.
Of an estimated 17 gangland killings this past year, five were in Limerick.
According to its annual report, achievements by the NCS included an increase in the number of alleged gangland bosses arrested.
He is still waiting to release the Irish gangland movie Gangs of New York.