Gardaí hope to know in the coming days if DNA samples taken from the getaway vehicle used in the fatal Bray gun attack can identify the gunman.
Officers are in the process of sending DNA swabs to Forensic Science Ireland, where scientists will generate a profile and run it through the DNA Database to see if there is a match.
Gardaí are also examining a “mountain” of CCTV footage, including from where the getaway van was abandoned and from the area surrounding Bray Boxing Club.
A gunman, wearing “headgear”, entered the gym room of the club at around 6.55am on Tuesday, just as a fitness session was about to begin, and opened fire.
There were between 15 and 20 people attending the gym class at the time.
One of the participants, Bobby Messett, was standing closest to the shooter and suffered traumatic injuries to his head and died almost instantly.
The 50-year-old father of three has been described by gardaí as a “totally innocent person, in the wrong place at the wrong time”.
Gym trainer, boxing coach Pete Taylor, was shot in the torso, while a second participant, Ian Britton, was shot three times in his right leg.
Gardaí believe between six and 10 shots were fired, and officers said that even more people could have been seriously injured.
Detectives are investigating why the gunman carried out the shooting and why he was so reckless.
They are investigating if the gunman was targeting Mr Taylor and, if he was, why he did it in a packed gym room rather than shoot the 57-year-old dad of Katie Taylor when he was on his own.
DNA samples have been taken from the van as well as fingerprint and fibre samples.
“We’d hope there is DNA in there,” said a source. “We’d have them swabbed and generated in the next few days.”
The profile will be run against the DNA database’s reference index, which holds existing DNA profiles of people, and the crime index, which holds unknown profiles taken from crime scenes.