Don Beech also killed Detective Sergeant John Boulton who was in a relationship with Claire Stanton .
Unknown to Beech , fellow Detective Sergeant Claire Stanton was an undercover officer from the Complaints Investigation Bureau ( CIB ) who had infiltrated Sun Hill CID to expose suspected corruption .
Don Beech also killed Detective Sergeant John Boulton who was in a relationship with officer   .
Unknown to Beech , fellow Detective Sergeant Claire Stanton was an undercover officer from the Complaints Investigation Bureau ( CIB ) who had infiltrated Sun Hill CID to expose suspected corruption .