Gangland murder victim Kenneth O'Brien was shot once in the head before the mob who killed him dismembered his body with a power saw.
Gardai believe the 33-year-old father-of-one was shot dead within hours of leaving his Clondalkin home on Friday, January 15, and the chief suspects are a ruthless west Dublin drugs gang.
Confirmation that he was shot was given yesterday by deputy state pathologist Dr Michael Curtis when he examined Mr O'Brien's severed head, which was found in the Grand Canal near Sallins, Co Kildare, on Monday.
There were no signs of torture on the victim's body, and it has emerged that the victim's head and limbs were found in bin bags and a sports bag.
Detectives believe the gang wanted the body parts to be found to send a grim warning to anyone who dared to swindle them.
Investigations are continuing to focus on a west Dublin heroin-dealing gang with whom Mr O'Brien is believed to have been in dispute.
It is understood he had been either laundering their cash or providing them with money for their trafficking network before they fell out.
Detectives are satisfied Mr O'Brien's murder was well planned and his killers did not panic when they dumped his remains at different locations in the Royal and Grand Canals.
"In all probability, this gang knew that this man's remains would be found quickly, and those responsible for the murder don't seem too bothered about this," a source said.
"The belief is that they wanted to send out a sick message to their rivals or anyone else who might think of ripping them off. There would have been many easier ways of disposing of the body.
"O'Brien was used by this criminal network because he was a clean pair of hands and was under the garda radar. There is no doubt that the victim got in and was out of his depth."
Gardai believe the gang scattered the remains at different locations to hinder the investigation.
Mr O'Brien's body was discovered on January 16 in the Grand Canal near Ardclough, Co Kildare.
Gardai said last night that they were continuing to search three locations in Kildare for further evidence.