The murder of Mark Lovell outside of his home last Thursday sent shockwaves throughout the city.
Police have heightened their presence in the area over concerns the violence could escalate.
The 58-year-old father was shot up to 15 times outside his home in Ardcarn Park.
He had been living in the house with wife Eileen, who has been threatened and ordered to leave Newry.
His killers were waiting when he parked outside the bungalow at the top of a hill in the estate.
Mr Lovell’s had been the victim of a previous gun attack in October, when a house belonging to him in Dundalk was targeted.
Norman Haslett, PSNI district commander for Newry, Mourne and Down, yesterday called for calm.
“Local residents will see an increase in the visible police presence in the area in the coming days and weeks,” he said.
“I would like to appeal for calm and the last thing anyone wants to see is any form of retribution.”
His colleague Detective Chief Inspector Anthony Kelly said: “Mark Lovell was a much-loved husband and father and was cruelly and callously gunned down as he drove towards his own home in the early evening.
“This appalling murder occurred at a time when local people were out and about, and indeed many neighbours who heard the gunshots immediately ran to provide what assistance they could.
“We believe those responsible went to great lengths to plan their attack and lie in wait for their victim to essentially ambush and execute him.
“They have shown a startling lack of regard for human life and have left a devastated and bereft family in their wake.”
A source revealed that two gunmen casually walked up to the car and opened fire.
The vehicle then rolled off and hit a nearby property, with the killers not leaving before making sure Mr Lovell would not survive this time.
When the first shots rang out his wife ran out of the house and was confronted by the horrific scene.
The source also said Mr Lovell may not have been the original target, with the gunmen choosing to take him out as a message to his son, Ebony Hughes.
“The talk is they were looking for Ebony,” the source said.
“If he was going to be there, well and good, but anyone else would do.
“That’s what you are dealing with here. They are absolutely ruthless.”
Mr Kelly appealed for help from the public to aid the police probe.
“Our murder investigation continues apace, and we are working to establish a definitive motive for the killing,” he said.
“I would urge anyone with information and anyone who may have captured dash-cam or any other footage in the area at around the time of the murder to please get in touch with detectives.”