The man was arrested by detectives in the Belfast area yesterday afternoon and was also questioned about the attempted murder of five other people.
Police are investigating the murders of sappers Patrick Azimkar, 21, from London, and Mark Quinsey, 23, from Birmingham in Massereene Barracks.
The soldiers were the first to be murdered in Northern Ireland in 12 years.
Two men have so far appeared in court charged with murdering the two soldiers.
