Costello was the captain of a commercial fishing vessel, the GulfCoaster, in 2005. He was last seen on February 27, 2005. He was with another man, John Molina, on the GulfCoaster in the Gulf of Mexico, 73 miles away from John's Pass, Madeira Beach, Florida. Costello has never been heard from again.

The United States Coast Guard began searching for the men and boat on February 28, the day after they were last seen. On March 2, debris from the GulfCoaster were located floating in the ocean, as was Molina's body. Costello was never located, however. He is believed to have died in a mishap at sea.