WASHINGTON?Government scientists have a strategy they hope will help lead them to the sender of a letter to Sen. Patrick Leahy that is believed to contain anthrax, the FBI said Monday.

The bureau said investigators are convinced the letter to Leahy and an anthrax-laden letter to Senate Minority Leader Tom Daschle were sent by the same person.

The FBI and the Army’s laboratory at Fort Detrick, Md., were working with a panel of experts on a plan to analyze the still-unopened Leahy letter.

“FBI and Centers for Disease Control investigators hope that this careful, scientifically agreed upon approach will yield clues that will help identify the source,” the FBI said in a statement.

The Leahy letter was found Friday evening by the FBI and hazardous materials personnel in one of 280 barrels of unopened mail sent to Capitol Hill and held since the discovery of the letter to Daschle.