Manners suggest when corresponding with a financial firm regarding sagging tech stock prices, it's best to avoid threatening a senior officer with his fiery end at the hands of the Prince of Darkness.

More importantly, sending a disarmed pipe bomb to emphasize your point is — while often compelling — frowned upon in high society.

John Tomkins, a machinist in a Dubuque, Iowa manufacturing company, has been arrested today for ignoring these basic rules of charm school.

Federal agents believe they have apprehended the so-called "Bishop Bomber," who has mailed more than a dozen threatening letters to financial institutions since 2005. The Bishop's uncouth investment proposals usually involved references to heaven and hell and demanding stocks be adjusted to his wacky satisfaction.

In January, the Bishop had sent parcels to investment firms Janas Small Cap and American Century. Each package was booby-trapped with a pipe bomb intentionally disarmed by disconnected wire to the firing circuit, but otherwise fully functional. Inside each package was a typewritten letter containing the message "BANG!! YOU"RE DEAD."

The Bishop's apparent strategy: having suitably grabbed the recipient's attention, tell the investors further along the letter there would be a rally over three consecutive days in early February in technology and entertainment company Navarre Corp stock.

Sixteen other letters were sent to investment companies since May 2005 postmarked from a suburb in Chicago and in Milwaukee. Several of these demanded the stock of computer networking company 3Com be raised to $6.66.

On Oct. 25, 2005, a letter to an investment company executive contained a picture of the exec's house with the words "DO YOU KNOW WHO LIVES HERE? I DO" and "REMEMBER COMS 6.66 10/31/2005" written on it.

3Com's third quarter results had shares trading at $3.82, suggesting The Bishop wasn't thinking critically about this. Perhaps a bit eccentrically, one could venture.

Reports obtained by the US Securities and Exchange Commission identified Tomkins as the only individual investor holding interests in 3Com and Navarre that would have increased in value had the securities moved in the Biblical direction demanded.

The US Attorney of the Northern District of Illinois reports on April 11, agents conducting surveillance of Tomkins in Dubuque observed him driving a red 1993 Chevrolet Lumina with an interior matching what was visible in the photograph of the investment executive's home.

The complaint also lists handwriting samples from Tomkins bank signature card, mortgage, and employment documents that allegedly match handwriting on envelopes from The Bishop.

Sales records show PVC pipes and caps consistent with materials used in the pipe bombs were purchased using Tomkins' credit card.

Tomkins was charged today with one count of mailing a threatening communications with intent to extort and once count of possession of an unregistered destructive device. He will appear before US Magistrate Judge Sidney Schenkier in the District Court in Chicago.

The first charge carries a maximum sentence of 20 years in prison and the second a maximum of 10 years. Both carry a maximum fine of $250,000.

So remember your good manners, readers. Always be polite and register your pipe bomb before sending it to your favorite tech company. ®