Sheriff's divers searching offshore Tuesday located a sunken boat believed to belong to the missing brother of U.S. Democratic Reps. Loretta and Linda Sanchez.

The boat was found upside-down at a depth of 150 feet, Coast Guard Ensign Stephanie Young said.

Authorities began searching for the boat Thursday after Henry Sanchez, 51, and his girlfriend, Penny Avila, 48, both of Santa Ana, vanished on an overnight trip from the mainland to Santa Catalina Island. Wreckage was found floating five miles south of the entrance to the Port of Los Angeles.

Young said there were no reports of bodies found in the wreckage of the Bayliner pleasure boat.

Officials have been looking into whether the boat was in a nighttime collision, possibly with a barge. Divers plan to refloat the hull Wednesday and tow it back to shore so it can be used as evidence in the investigation.

Young said the sunken boat is believed to be the missing 26-foot Bayliner based on past photos of the vessel and the location near the suspected collision site.

The area is busy with maritime traffic outside the adjacent Los Angeles and Long Beach harbors, the nation's largest port complex.

Loretta Sanchez, 48, is in her sixth term representing the 47th District in Orange County. Linda Sanchez, 39, is in her third term representing the 39th District in Los Angeles County.