Although the information came from Italian investigators, he said, "there's zero confirmation about this possibility."

An American general says the plane was following a standard training route, and thus far the crew have refused to speak with Italian investigators.

In practice, Italian investigators are concerned with more recent traffic, mainly since the 1970's.

However the information obtained was not given to the Italian investigators.

Several senior Italian investigators said they believed the 13 operatives had left Italy.

Italian investigators initially did not take the term seriously, believing it was used only by the American Mafia.

The death was considered by Italian investigators to have been suicide.

And in the 120 interrogation sessions with Italian investigators, he never fully explained his motives for trying to kill the pope.

"We do feel quite betrayed that this operation was carried out in our city," a senior Italian investigator said.

American and Italian investigators should point their efforts toward possible criminal prosecution, with appropriate punishment for anyone proved responsible.