Boko Haram sect on Friday posted a picture of three staff members of the University of Maiduguri (UNIMAID) it abducted on Tuesday.
The men were abducted during an ambush of oil exploration workers in the Lake Chad Basin by the terror group.
At least 48 people were reportedly killed during the ambush.
The bodies of the victims have been deposited at the University of Maiduguri Teaching Hospital (UMTH) mortuary.
Corpses deposited were remains of 18 soldiers, 15 civilian JTF members, five university staff and four Nigerian National Petroleum Corporation (NNPC) drivers.