SALT LAKE CITY (AP) — The bodies of two men have been recovered from the wreckage of a small plane that went missing late last month in northwestern Utah, authorities said Sunday.

Box Elder County Sheriff’s officials said divers began the recovery operation at about 7:30 a.m. Saturday and it took about four hours before the bodies of 71-year-old pilot Denny Mansell and 74-year-old passenger Peter Ellis could be pulled from the Great Salt Lake.

The wreckage was in about 20 feet of water near Promontory Point but sheriff’s officials said the operation was “extremely technical” and hampered by the position of the plane, which was upside down at the bottom of the lake.

The Cessna 172 was reported missing after it didn’t return to the Ogden airport following a Dec. 29 sightseeing trip.

The men reportedly intended to fly over a re-enactment event at the Golden Spike National Historic Site near Promontory Summit.

Air and ground searches failed to locate the plane, but teams using sonar discovered what appeared to be the aircraft on the lake’s north end last weekend.

Fog and poor conditions on the lake delayed recovery efforts.

Further investigation of the crash and bringing the wreckage up will fall to the National Transportation Safety Board and the plane’s insurance carrier, according to the sheriff’s office.

The bodies of the two men were transported to the Utah Medical Examiner’s Office for autopsies to determine the cause of death.