The Army has never reviewed ocean dumping records from that era and doesn't know where those dumps might be, William Brankowitz said. He's a deputy project manager in the Army Chemical Materials Agency and a leading authority on the Army's chemical weapon dumping.

The Corps of Engineers is investigating whether it was part of a 1964 Army dumping operation that might not have disposed of everything in its intended deep-water burial. It was one of few known dump operations in which 75 mm shells were tossed into the Atlantic Ocean.

Surviving Army records show that in 1964 a barge dumped 1,700 75 mm artillery shells with mustard gas and tons of steel containers full of mustard gas and cyanogen chloride - which can cause convulsions, unconsciousness and death.

The chemical weapons were loaded onto the barge at Edgewood Arsenal in Maryland and pulled by another ship down the Chesapeake Bay, into the Atlantic Ocean and headed north.

The five-day operation was supposed to dump all its deadly load in deep water, Williams said the Army told him.

Army records show that the barge was unloaded off the Virginia-Maryland state line.

The records give no explanation why a barge headed there would go so far north, then south again to dump its load.

There is, however, a plausible explanation how some of those chemical weapons might not have reached their intended dump zone.

Along the way, a 1-ton steel container of mustard gas was found to be leaking, a little-known 1987 Army report indicates.

The barge was evacuated. The crew donned protective suits on an accompanying ship, then went back to the barge.

They decontaminated the deck with chlorine, which neutralizes mustard gas, and threw the leaking container and another contaminated container over the side.

Either other chemical weapons on deck were tossed overboard, as well - or the ship's captain said, " 'It's Friday,' or 'I don't want to go all the way out there. Throw it over,' " Williams guessed.