A 36-year-old man who was subject to a "brutal killing" in north Belfast was shot at multiple times by a single gunman, a senior PSNI detective has said.
Robbie Lawlor from Coolock in Dublin was targeted at a house on Etna Drive on Saturday afternoon.
Three men and a teenager have been arrested in connection with the killing and are being questioned in the Serious Crime Suite in Belfast.
The men are aged 33, 27, and 30 and the teenager is 17-years-old.
Detective Superintendent Jason Murphy said: "At this stage I believe that a single gunman was involved in the killing, firing multiple shots at the victim and striking him a number of times. The murder weapon has not yet been recovered.
"Two properties, one in west Belfast and one in Crumlin were also searched as part of this murder enquiry.
Mr Murphy added: "I do not believe that Robbie was in the Ardoyne yesterday by accident. I believe he had some reason to be there and key lines of enquiry for me at this stage are to establish why he was there and what his connection to the address is.
"This was a brutal killing and I am appealing for the public's help to bring the gunman to justice. I would like to hear from anyone who was in Etna Drive yesterday, between 11am and 12.30pm, and who may have witnessed the shooting or the gunman making his escape.
"I'm also keen to speak to anyone who can help us trace the movements of a VW Scirocco car, registration YLZ 7052. I believe it was in Estoril Park on Friday and was burnt out in Kingston Court immediately after the murder yesterday."
The killing has been condemned by local politicians.
Justice minister Naomi Long condemned the "senseless murder", and offered her sympathies to the man's family.
Sinn Fein MLA Gerry Kelly appealed for calm in the area, and urged anyone with information to speak to police.