CANBERRA, Australia (AP) — Investigators searching for the missing Malaysian jet have concluded an area where acoustic signals were detected is not the final resting place of the plane after an unmanned submersible found no trace of it, the search coordinator said Thursday.

The U.S. Navy’s Bluefin 21 finished its final underwater mission in the southern Indian Ocean on Wednesday after scouring 850 square kilometers (330 square miles), the Joint Agency Coordination Center said.