Sandie Egley, director of business development for Marion Hill Associates, which is participating in the search, said crews believe they may have spotted the missing plane's propeller underwater, but divers were unable to recover the artifact, the Pittsburgh Tribune-Review reported Monday.

"We can't positively ID it as the B-25, but we think it's the propeller," Egley said. "The ghost remains."

The B-25 Recovery Group said the plane is believed to have floated downstream and sank Jan. 31, 1956, after it ran out of fuel on its way to Harrisburg, Pa.