The body of the third and final registered occupant of a small plane that crashed Sunday into a deep Mississippi River island quarry was recovered overnight Thursday, the Washington County Sheriff's Office said Friday.

The investigation into what caused the crash will continue, authorities said.

The third victim's name has not been released. The other two victims were identified Thursday night. Larry Schlichting, 60, of Eagan, and Lucas Knight, 24, of North Mankato, Minn., were killed in the crash, according to the Ramsey County Medical Examiner's Office.

Authorities did not say whether one of the two identified men was piloting the plane.

Working in water up to 70 feet deep, searchers recovered the first two bodies Thursday afternoon from the privately owned quarry on Grey Cloud Island, and the third one late Thursday.

Search and recovery operations were challenging because the walls of the 200-foot-deep quarry are sand-based.

The single-engine Cessna aircraft left Fleming Field Municipal Airport in South St. Paul sometime after 2 p.m. Sunday. Authorities were notified that it was missing Sunday night, and the first signs of wreckage were discovered just before midnight Sunday.

Knight, who was originally from Coon Valley, Wis., graduated from Minnesota State University, Mankato in 2019. His social media profiles say he studied aviation.

Schlichting worked as a technical writer at MTS Systems Corp. in Eden Prairie and attended St. John's University in Collegeville, the University of Minnesota and Concordia University, St. Paul, according to his online obituary.