The man under suspicion is a known gangster from north Belfast who is currently on licence after he was released halfway through a jail sentence for stabbing a friend to death.
According to a senior loyalist source, he is now "a marked man".
Former UDA boss Boreland was shot dead near his home in north Belfast last Sunday just minutes after leaving his local bar. His murder is believed to be part of a turf war between factions of the UDA in the north and south of the city.
In a bid to try and calm tensions, the UDA in north Belfast yesterday announced it had changed its leadership.
A group calling itself the North Belfast UDA Brigade staff said the move was "in response to a crisis in confidence in the past leadership".
"We were not prepared to stand by and watch as our organisation was being brought into disrepute," the group said in a statement.
The statement added that the new leadership would be "committed to community development and loyalist common sense politics" and "offer a policy of discipline, unity and purpose".
However, the Belfast Telegraph has learned that the new leaders are two drug dealers who do not have the community's support.
"This won't stop the feud. The feud won't end until those behind Boreland's death are killed. I'd say you will see another two shootings before it is over," a senior loyalist source said.
So far one person has been arrested in connection with the murder, but later released without charge. The shotgun used in the attack has not been recovered.
Last night police returned to the scene of the shooting to make further inquiries.
They want to speak to those who were in the bar on the Oldpark Road with Boreland shortly before his murder and to anyone who spoke to him after he left. Police are also keen for anyone with information about a silver Renault Megane - registration number GJZ 4870 - that was found burnt out at the entrance to the old quarry on Wheelers Road in Lisburn at 9.30am on Tuesday.
They are also interested in the movements of a black Peugeot 307 car which was travelling along Sunningdale Gardens in the direction of Sunningdale Park.