"Who's Buried in Superman's Tomb?"
Triangle 1993-8. Continued from Adventures of Superman (1987) #499 and continues in Superman: The Man of Steel #21.
After catching some criminals to blow off a little steam, Guardian finds that something strange is going on in a secret vault at Cadmus. Meanwhile, Supergirl, Metropolis S.C.U., and Lex Luthor try to figure out who stole Superman's body and where it is.