MISHICOT, Wis. (AP) — Investigators searching for a missing woman found burned human remains at a salvage yard owned by the family of a man who spent 18 years in prison for a rape he did not commit.

Sheriff Jerry Pagel said authorities were working Thursday to identify the pieces of bone and teeth. Relatives of the missing woman, photographer Teresa Halbach, found her sport utility vehicle at the salvage yard on Saturday.

"It appears that an attempt was made to dispose of a body by an incendiary means. However, that attempt was not completely successful," Pagel said.

Pagel also said investigators found the key to Halbach's SUV in the bedroom of Steven Avery, whose family owns the salvage yard. Avery was freed from prison in 2003 after DNA evidence cleared him of a rape conviction.