Pipe bombs found in mailboxes in Illinois, Iowa and Nebraska were nearly identical and came from the same source, the Federal Bureau of Investigation (FBI) announced on May 6 in Washington.
FBI agent Larry Holmquist said that the bombs were made with the same material, the only difference being in their detonation mechanisms.
"There is no question that these were planted by the same person or persons," Holmquist said, adding that the anti-government letters accompanied the bombs also were identical.
A total of 15 pipe bombs were found in the three states. Six people were injured by explosions in Illinois and Iowa on Friday. Two other bombs found in Iowa did not explode. Six bombs were found on Saturday in rural areas of Nebraska, and two suspected bombs -- one of which turned out to be a hoax, were reported to authorities in Nebraska, on Sunday.
Some residents of Iowa and Nebraska have had to make modifications to their mailboxes to receive their mail under procedures initiated by the US Postal Service.
At a news conference on Sunday, Mike Matuzek, US Postal Service district manager for the central plains, asked owners of "rural style mailboxes" to remove the door of the mailbox or fix it in such a way that the door can not be closed without significant effort.
Mail delivery was suspended on Saturday in rural northeast Iowa and part of northwest Illinois after Friday's explosions.
FBI described the placing of bombs as "domestic terrorism." Thebombs came just seven months after the Postal Service was rocked by the anthrax scare that killed five people on the East Coast.
( May 7, 2002)