James McConnell, 38, was gunned down by two masked men in his home in the Woodland Avenue area of the city in February 2009.
The suspect was arrested in Dungiven and has been taken to the PSNI's Serious Crime Suite at Antrim police station.
The man is also being questioned about a shooting incident in the village of Feeny in Co Derry in 2004, when a shotgun was fired at a house.
Detectives have also undertaken two searches in the Dungiven area.
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