KINGSTON, Jamaica (AP) — Crews searching off Jamaica’s northeast coast on Saturday were stymied in efforts to solve the mystery of a small private plane carrying a prominent New York couple that took a ghostly 1,700-mile journey after the pilot was apparently incapacitated.

Jamaica Coast Guard spokeswoman Antonette Wemyss-Gorman told a news conference Saturday that debris spotted off the coast Friday could no longer be seen. “We would have to assume it may have sunk,” she said.

Maj. Basil Jarrett of the Jamaica Defense Force had said earlier in the day that possible wreckage of the high-performance plane was spotted Friday evening by a military aircraft flying off the island’s northeast coast, floating roughly 24 miles off the coastal town of Port Antonio.

Leroy Lindsay, director of Jamaica’s civil aviation authority, said the area where the private U.S. plane went down has depths of up to 6,500 feet. The Jamaican military on Friday had reported finding an oil slick in the general area where the plane vanished.

Lindsay said that once the wreckage is located, French authorities have offered to provide expertise and equipment to bring it up from the ocean depths because the airplane was French-made.

The single-engine turboprop Socata TBM700 was carrying Rochester real estate developer Laurence Glazer and his entrepreneur wife, Jane – both experienced pilots.

The Coast Guard in Miami said three people were reportedly on board the plane. A 154-foot U.S. Coast Guard cutter and a helicopter crew are aiding in the search off Jamaica.

The plane’s pilot had indicated there was a problem and twice asked to descend to a lower altitude before permission was granted by an air traffic controller, according to a recording of the radio conversation. Radio contact with the plane was lost shortly thereafter.