A letter carrier whose calling card was “The Bishop” was sentenced this week for mailing pipe bombs to investment firms.

According to an Associated Press report, John Tomkins of Iowa was sentenced to 37 years in prison this week for mailing “dud” pipe bombs to investment firms and investment advisers. The 48-year-old mail carrier had mailed the ineffective pipe bombs with letters signed “The Bishop,” an idea he stated he got from criminals in movies. He will serve a manditory minimum sentence of 30 years.

Tomkins’ crimes were reportedly a scheme to influence the value of stocks that he owned. The letters mailed along with the intentionally disabled bombs had threatened financial executives and their families if stock prices were not raised for certain companies.

According to the AP report, it took U.S. authorities two years to track down Tomkins. The crimes were eventually pinned to him using the stock market records of two companies Tomkins had mentioned in his threats.