Gardaí believe they know who murdered drug dealer Mark Desmond and suspect the Kinahan crime gang is linked to the killing.
Last week gardaí arrested a total of five people as part of their inquiries into the shooting dead of Desmond last December.
They have all been released without charge but the investigation is continuing.
The 41-year-old's body was discovered in open parkland at Griffeen Valley Park, Lucan, on the night of Friday, December 2nd, 2016.
From Ballyfermot, Desmond had been convicted of unlawful possession of firearms with intent to endanger life and was a suspect in a number of gangland-style killings in Dublin over the past two decades.
He was regarded as a significant player in the drugs trade and had a large number of enemies.
Gardaí believe he had made threats against a Dublin man who was working for the Kinahan gang.
The Dubliner fled Ireland for Spain over fears he may be shot dead at Desmond's behest. Gardaí believe the Kinahan gang arranged for Desmond to be killed as a result
It is believed he went to meet a man he trusted in Lucan on the night he was killed and was ambushed there.
Detectives believe they know who fired the fatal shots at Desmond and also the identity of two other men who were central to aiding the killing, including a getaway car driver.
Desmond had been charged with the murders of Darren Casey (19) and Patrick Murray (20). Their bodies were taken from the Grand Canal in Co Kildare in January 2000. They were shot dead and remains thrown into the canal with no effort to conceal the killings.
However, when the case went to court the evidence of a key witness was withdrawn and Desmond was convicted only for possessing a firearm.