A 37-year-old was also being questioned about the attempted killing of five people in a shooting outside Massereene Barracks in Antrim in March.
A report has been passed to the Public Prosecution Service.
The man was arrested yesterday in Bellaghy, Co Derry, by detectives investigating the murder of Sappers Patrick Azimkar and Mark Quinsey.
The soldiers at Massereene Barracks were the first soldiers to be murdered in Northern Ireland in 12 years.
41-year-old Colin Duffy from Lurgan is one of two men charged with the murders.
He has been in custody since March.
