Former University of Wisconsin-Stout student Luke Helder, accused of planting pipe bombs in mailboxes throughout the country, will plead insanity when he goes on trial Nov. 18, court records show.

Jane Kelly, Helder’s lawyer, filed a notice of an insanity defense with Judge Mark Bennett and the U.S. District Court of the Northern District of Iowa. Kelly said she plans to use expert witnesses to testify to Helder’s mental condition.

Helder is accused of depositing 18 pipe bombs in mailboxes in Iowa, Illinois, Nebraska, Colorado and Texas in early May. Six of the bombs exploded, injuring four letter carriers and two residents. He told officials he had been attempting to map out a smiley face.

The 21-year-old from Pine Island, Minn., also authored anti-government letters, including one sent to The Badger Herald which warned, “I will die/change in the end for this, but that’s ok, hahaha paradise awaits!”

Those who know Helder best have kept mute on the issue of his mental state. Kris Anderson, a UW senior, went to high school with him and said back then he was just an average student.

“He may have had some weird ideas, but I think every high-schooler has some f*cked-up ideas,” she said.

However, Anderson said it was possible Helder has mental issues.

“He didn’t seem really crazy in high school, but you can keep a lot from people when you’re only with them a few hours a day,” she said. “You can present what you want to present.”

UW associate law professor Keith Findley said an insanity plea is hard to prove.

“It is very, very difficult to meet the standard of insanity,” Findley said. “It happens very infrequently.”

Advantages to successfully pleading insanity are that the convict is entitled to treatment and also may have the opportunity to be released when psychologists see fit. However, cautions Findley, an insanity plea does not mean the convict is off the hook.

“If you’re found insane, you don’t go free,” he said. “You go to a mental hospital that is very similar to a prison.”

In addition, he said, courts are “very conservative” on deciding when to release convicts.

Helder faces charges in Illinois, Nebraska and Iowa. He was arrested May 7 outside Reno, Nev., and returned to Iowa May 10, where he remains in custody in the Linn County Jail. He is charged with using an explosive to damage personal property, which resulted in an injury to a person, and using a pipe bomb during a federal crime of violence.