A senior police officer said the investigators will also analyze the CCTV footage in the surroundings to find any clues of the assailants.
He added that statements from family members are being recorded.
The drive-by shooting took place on Gnanendra Road in Ratmalana when the victim, Ranjan de Silva was chatting with few friends in front of his house.
Initial investigations revealed that T-56 weapons were used in the crime.
Police said that Ranjan de Silva had been shot 12 times.
Meanwhile, a spokesperson from Kalubowila Hospital said that the other two victims who were injuries are not in a critical condition.
Police further said that CCTV footage will be analyzed as part of the ongoing investigation.
62-year-old, Ranjan de Silva of Beach Road, Ratmalana was a member of the Dehiwala - Mt. Lavinia Municipal Council.
He was elected to the council from Sri Lanka Podujana Peramuna after winning at the February 10th Local Government Election.
Meanwhile, Dhananjaya de Silva who was to leave for West Indies with the Test squad has withdrawn from the team.