Louis Robert Piatt was last seen alone in a rented kayak one and a half miles off the Malibu Pier in Los Angeles, California on the afternoon of December 29, 2011.

He started his trip at 1:30 p.m. and, at approximately 3:00 p.m., he called 911 from his cellular phone. He was breathing heavily and complained of of chest pains. He stopped speaking and the conversation was cut off before he could tell the operator exactly where he was, and it took an hour for the rescue squad to find him. By the time they arrived, Piatt had vanished and they only found his overturned kayak with a life vest attached.

He had left his vehicle in a parking lot near the pier.

The Coast Guard's 23-hour search, covering 110 square miles, turned up no sign of Piatt. Witnesses did see a 30- to 40-foot motorboat speeding away from near where he was last seen, just before search-and-rescue helicopters arrived. The boat had a very wide rear stern, a dark-colored hull, a white superstructure and a fly bridge-type enclosure astern.

Piatt lived in Pacific Palisades, California and was a real estate executive at the time of his disappearance. He had served as second lieutenant in the Marines during the Vietnam War. His case remains unsolved. Authorities haven't ruled out the possibility that he could still be alive. (Information retrieved from NamUs.gov)