April 25, 2007 -- An arrest was made at 8:03 a.m. EDT in the case of the so-called "Bishop Bomber" who in January mailed a package containing an explosive device to a Kansas City investment firm.
Police described the suspect as a 42-year-old former postal worker. He is expected to be arraigned later today.
Sources say that the U.S. Postal Service has the suspect in custody in Dubuque, Iowa, and that police hope they have averted a serial killing spree.
When a mail clerk at the Kansas City investment company opened a package in late January, it read, "BANG YOU'RE DEAD."
Sources tell ABC News the package, sent by someone who called himself "The Bishop," contained a pipe bomb filled with explosives, along with the wiring and triggering mechanism to detonate the device.
ABC News has learned the bomb would have exploded, but the Bishop intentionally did not connect the trigger wires.
In an attached letter, the would-be bomber warned that if his demands were not met, the next device would kill.
"If you look at the devices that he mailed this time, absent specific components, that all he has to do is put these components in and that next time he will hurt somebody," said Fred Burton of Stratfor security firm.
The Bishop has threatened businesses in the Midwest since May 2005, demanding that financial firms set a number of specific stocks at $6.66 per share, an apparent satanic reference.
In one letter, the Bishop wrote, "It is so easy to kill somebody, it is almost scary. Just think, it could be as simple as mailing a package just like The Unibomber use [sic] to."
Police have said they were in a race against time to stop the Bishop from putting those words into action throughout the U.S. mail system.