Gardai are seeking to arrest a number of people based outside Ireland over the feud murder of Eddie Hutch, an inquest into his death heard.
Mr Hutch (58) died of gunshot wounds to the head after he was shot at his home at Poplar Row, Ballybough, Dublin 3, on February 8, 2016.
Gardai have completed 1,203 actions in the investigation, Dublin Coroner's Court heard.
Two relatives of Mr Hutch sat in the public gallery as Inspector Aidan Flanagan applied for a 12-month adjournment of the inquest.
"We have completed 1,203 investigative tasks in relation to this case. There are still a number of tasks to be completed," he said. "There are a number of arrests yet to be made, some of whom reside outside the jurisdiction," Insp Flanagan said.
Some of those who are abroad are key hitmen for the Kinahan cartel, including a Cabra criminal who is a former close associate of Martin 'Marlo' Hyland.
The inquest was previously opened and adjourned after Mr Hutch's brother, John, gave evidence of identifying his body.
John Hutch told how he attended the Dublin city morgue to identify his brother's body on February 10, 2016.
"I was shown my brother Eddie in the morgue. I am 100pc certain it's my brother," he said.
The inquest was further adjourned last March for six months following a garda application as the investigation continued.
Coroner Dr Myra Cullinane asked family members if 12 months was agreeable to them and they said it was. She granted the application, adjourning the inquest until September 3, 2019.
Mr Hutch was gunned down by a four-man hit team as he returned to his home.
Of the nine people arrested, one was picked up by armed gardai in a raid on his north inner city home in February.
The man, who is in his 30s, has been the subject of a sinister graffiti campaign by the Hutch gang in recent weeks in Dublin's north inner city.
The man has been branded a "rat", which has stoked the feud and contributed to the two latest deaths linked to it.
He was released without charge but gardai are hopeful of rearresting some of these suspects.