A man arrested yesterday in connection with the death of a builder in an explosion at a Territorial Army camp in Derry has been released without charge.
He was detained in the Sion Mills area yesterday by detectives investigating the murder of Mr David Caldwell.
Mr Caldwell (51), died after picking up a lunchbox packed with explosives in the Caw Camp outside the city last Thursday.
The man was the sixth person to be arrested and released without charge by officers investigating the case. The other five detainees, four men and one woman, were freed on Saturday.
Security sources have pointed to the involvement of the "Real IRA" in the attack.
Several hundred people walked from the camp to the city's Guildhall Square on Monday in protest at the killing.