HAMMOND, Ind. (AP) — A man charged in a pipe bomb explosion at a northwestern Indiana post office says he was targeting an attorney who had filed a lawsuit against him.

Eric Krieg of Munster, Indiana, pleaded guilty Tuesday to making an unregistered destructive device and other charges. He likely faces 29 years in federal prison.

In a court filing, Krieg says he mailed a pipe bomb on Sept. 6, 2017, that targeted an attorney who was representing someone in a lawsuit against him. Krieg says he hoped the explosive would “kill or injure” the lawyer. The bomb exploded at the East Chicago post office, injuring a worker.

Krieg also admitted that he mailed a threat to kill or injure another person. U.S. Attorney Thomas Kirsch says Krieg’s “egregious” conduct put lives at risk.