Published Tuesday, 04 August 2009
Sappers Mark Quinsey and Patrick Azimkar were shot dead as they collected a pizza delivery outside Massereene Army Barracks in March.
Two delivery men were also wounded in the attack, for which the Real IRA claimed responsibility.
The 51-year-old was arrested on Tuesday in the Mid-Ulster area and held at Antrim Serious Crime Suite.
He was released unconditionally on Wednesday morning.
Prominent Co Armagh republican Colin Duffy was charged with the murders within weeks of the attack, and 44-year-old Brian Shivers, from Maghera, Co Londonderry, was charged with the killings 12 days ago.
When he appeared in court, police said they feared another suspect they were looking for had fled the jurisdiction.