Three men were arrested on Tuesday morning by detectives investigating the murder of prominent loyalist John Boreland.
A Police Service of Northern Ireland (PSNI) spokesman said a 29-year-old was detained in Scotland in the north Ayrshire area, with assistance from Police Scotland, and two men, aged 33 and 61, were arrested in north Belfast in connection with the fatal shooting of the 46-year-old last month.
John Boreland, a UDA leader, was shot a number of times on August 7th as he got out of his car to walk to his flat in Sunningdale Gardens.
He died at the scene.
All three suspects being linked to his death are to be questioned at Musgrave police station in Belfast.
The officer leading the investigation, Det Chief Insp Justyn Galloway from PSNI serious crime branch, said: "Officers have travelled to Scotland to assist colleagues from Police Scotland with the arrest and related searches.
"The investigation is progressing and I would again appeal for information about a silver Renault Megane car which was used by the killers. The car, registration number GJZ 4870, was in the Ballysillan area of north Belfast in the days leading up to the murder on Sunday 7th August.
“We are still very keen to hear from anyone who saw it, saw who was in it and where it had been parked. We are re-issuing two photos of a similar vehicle to enhance our appeal.
"We are also interested in talking to anyone who saw the Megane between the Sunday night of the shooting and when it was found partially burnt out at the old quarry on Wheelers Road near Lisburn on the morning of Tuesday 9th August," Mr Galloway said.
At the beginning of the investigation one man was arrested in Belfast but later released unconditionally.
Previously, a number of searches were carried out in Belfast and a vehicle was seized.
Anyone with information to contact the independent charity Crimestoppers on 0800 555 111.