Four people have been arrested by detectives investigating an attempted under car bomb attack on a policeman.
The booby trap device left was under the car of the officer at his home near Eglinton, Derry in June 2015.
The targeted man's wife was also a serving PSNI officer.
Three men, aged 29, 38 and 46, and a 32-year-old women were detained on Thursday.
The arrests were undertaken in Belfast, Derry and Pomeroy.
The suspects have been taken to Musgrave police station in Belfast for questioning.