Forensic experts said on Friday they had unearthed the remains of 456 people believed to have been wartime prisoners killed by Bosnian Serb forces in what is the second largest mass grave found so far in Bosnia. "We completed the exhumation of bodies from the Kevljani grave after we had reached the bottom at six meters (18 foot) depth," Esad Bajramovic, an official of the Commission for Missing Persons of Bosnia's Muslim-Croat federation, told Reuters by telephone. The experts were working on the 17 meter-long and six meter-wide grave in western Bosnia since mid-August. This is the second mass grave found in the village of Kevljani, near the town of Prijedor. Bajramovic said documents found on some 40 bodies showed that the victims were prisoners of the Serb-run detention camps Omarska and Keraterm, also near Prijedor. Early in the 1992-5 Bosnian war, thousands of Bosnian Muslims and Croats were held, killed or tortured in three detention camps near Prijedor. Nearly 3,500 people went missing from the town alone.