SEATTLE -- Federal authorities said they found more than 100 guns at the home of a former Boeing Co. worker, who is charged with sending bomb threats to some of the company's top executives.

A grand jury returned a 16-count indictment Thursday against 46-year-old Gino Augustus Turrella, of Des Moines, charging him with making threats and identity theft. He was arrested Tuesday at an REI parking lot.

On Thursday, KIRO 7 News crews found a sign that says "gone fishing" outside his home which he shares with his mother, who told said, "I just can't believe he would do anything like that."

Turrella worked as a flexible machine operator in Auburn from August 1987 to August 2005, Boeing spokeswoman Kelly Donaghy said.

On May 2 and 4, Turrella sent e-mails to a Boeing server threatening to shoot up a Boeing building in Auburn or, alternatively, strap himself with explosives, FBI Special Agent Chad Piontek wrote in a federal complaint.

"I'm going for maximum death and destruction in the work place!" Turrella allegedly wrote.

One e-mail was addressed to several top Boeing executives, including Scott Carson, chief executive of the company's Commercial Airplanes division; Pat Shanahan, general manager of the 787 program; and Robert J. Pasterick, Commercial Airplanes chief financial officer.

Turrella used an e-mail address that appeared to belong to his former manager, who is identified in court papers only as J.O., and he signed the e-mail with his former manager's name, the agent wrote.

The investigation into those threats -- as well as similar threats sent later that month to the Shell oil refinery in Anacortes -- uncovered a long history of threatening behavior by Turrella that had previously come to the FBI's attention.

Through much of the 1990s he made threats over ham radio, including threats to kill people by AK-47, Piontek wrote, and he frequently jammed transmissions. The Federal Communications Commission fined him $10,000, but he never paid. In turn, Turrella threatened to bomb the Kirkland, Wash., FCC office, according to court documents. Despite witness statements and fingerprint evidence, he was given a deferred prosecution.

In 1997, the U.S. attorney's office in Seattle sent Turrella's lawyer a stern letter asking that Turrella stop interfering with communications on a Coast Guard emergency distress channel. The radio threats continued until 2000, Piontek wrote.

In late 2004 and early 2005, Turrella sent a co-worker, via interoffice mail, three separate, live AK-47 ammunition cartridges, two of them wrapped in threatening notes, the complaint said. Boeing eventually fired him for that, and an analysis by FBI behavioral analysts determined he "possessed many of the characteristics deemed to be risk factors for future acts of targeted violence," and there was a "low-to-moderate" risk that he would attack Boeing employees.

The complaint said Turrella had no criminal convictions. His attorney, federal public defender Robert Harris Gombiner, did not immediately return a call seeking comment.

Turrella is scheduled for a detention hearing Friday in U.S. District Court.