Gardaí say it will take several days before the remains found in a suitcase in The Grand Canal on Saturday can be identified.
The man's remains were found by youths walking along the waterway near Ardclough village at the weekend.
Gardaí in Leixlip are leading the investigation and they believe the man may have been killed at a house party on Thursday night before being dismembered and dumped in the water.
Former Detective Sergeant and cold case investigator Alan Bailey said that DNA will be key to unlocking the man's identity.
"DNA will be crucial," he said.
"There could be a historical medical or surgical intervention that might assist, it may be that someone had a broken arm or broken leg at some stage, or some operation scars on the torso, but for the most part, you're dependent on DNA.
"And to have that, you must also have a DNA sample, familial DNA from the missing person's family."