The missing 72-year-old American may have fallen overboard on the Princess Cruise

A 72-year-old American man disappeared while sailing on a Princess cruise ship, and officials suspect he fell overboard during his time on the ship.

A search began around 7 a.m. Monday after the cruise ship Ruby Princess docked in San Francisco and crews determined the man could not be found on board, according to the cruise company.

The cruise ship departed for Ensenada, Mexico on November 27th.

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The cruise ship departed for Ensenada, Mexico on November 27th. (Getty Images)

The man was alone on the cruise. It remains unclear when he may have exaggerated.

“Princess worked with local authorities throughout the day. CCTV footage was also thoroughly reviewed and the ship was thoroughly searched several times with no success,” a spokesperson for the cruise line told the New York Post.

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The missing man was traveling alone on the cruise. (Getty Images)

“Having ruled out other possibilities, this is being treated as a man overboard incident,” the spokesman added.

U.S. Customs and Border Protection is investigating the incident, a spokesperson for the cruise line told KTVU. The spokesman said Princess Cruises is cooperating with authorities in the investigation.