Police today launched an appeal for information about the murders of Edward Burns and Joseph Jones in Belfast on the first anniversary of their deaths.
"My team believes that there is someone out there who can tell us who is responsible — we need to talk to you," said Det Chief Insp David Cunningham.
The bodies of the men were found hours apart in Belfast last March 12th.
Mr Burns, 36, from the Ardoyne area of north Belfast, was found shot in the head in a car park near a GAA club at Bog Meadows off the Falls Road.
Mr Jones, 38, from Poleglass, on the western outskirts of Belfast, was found battered to death in an alleyway off Elmfield Street in the Ardoyne.
Police recovered a spade near the scene which they believe was used in the murder.
DCI Cunningham said the murder investigations were very much alive and ongoing.
He appealed: "If you saw suspicious activity in Bog Meadows on March 12th or at Elmfield Street in north Belfast, please contact 0845 600 8000 and ask for detectives."
On the anniversary of the killings detectives are carrying out house-to-house inquiries in the Elmfield Street area.
The killings were believed to be the result of tensions within splinter republican organisations but the Continuity IRA, suspected of involvement, denied responsibility.
A number of people, including a 16-year-old youth, have been questioned about the murders but no-one has been charged in Northern Ireland.
A 22-year-old woman was arrested and questioned for several hours yesterday before being released pending a report to the Public Prosecution Service.
However, one man is in custody in the south charged in connection with the killings.