CALDWELL, Idaho — A plea deal has been reached in the case of a Nampa man accused of threatening to set off bombs and release a deadly nerve agent at a Nampa apartment complex.

Grant Stevenson, 22, was arrested in March after police linked him to the online threats. 

According to his defense attorney, Peter Mommer, Stevenson will plead guilty to a felony terrorism charge as part of an agreement with prosecutors that would see a second charge of threatening to use weapons of mass destruction dropped.

Both sides have agreed to a prison sentence of 15 years behind bars, with three years before Stevenson can seek parole. Prosecutors will also ask for no more than $125,000 in restitution.

A terrorism conviction is punishable by up to life in prison. 

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Stevenson was charged after investigators say he sent a message to the Nampa Police Facebook page from a fake profile he had created under the name "Tony Abdul." The message began "death to America," and warned of a bomb containing sarin gas planted inside a unit at an apartment complex on South Juniper Street. 

The message indicated the sarin bomb would go off in one hour, and that five car bombs had also been set to explode as "deterrents." 

"We want u to watch as this bomb levels everything in a 400 yard radius fallout from this bomb will carry our deadly agent all across Nampa and into treasure valley," the message continued. "Do not attempt to stop us my men are already on move and timer is set now." 

"There is nothing u americans can do to stop it," follow-up messages read. "The calphite (sic) will prevail." 

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The threats drew an immediate response, mobilizing  Nampa Police, the FBI, ATF, and the National Guard, along with paramedics, Nampa Fire and a HazMat team. 

Skyview High School, Northwest Nazarene University and Nampa Recreation Center - all of which are near the apartments that were threatened - were placed on a six-hour lockdown, and residents in the area were told to shelter inside their homes.

Police turned their attention to Stevenson after a tipster reached out to Nampa Police, telling them that Stevenson had a history of making bomb threats against schools in the Treasure Valley, and was upset with a woman who lived in the apartment that had been targeted. 

Detectives also learned that woman and her boyfriend had received messages from the "Tony Abdul" Facebook profile, containing a picture of a person holding a gun coupled with threats to sexually assault the woman and kill her boyfriend. 

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In an interview with detectives, Stevenson denied making the bomb threat. In a search of his phone, however, investigators found Google searches for pipe bombs, car bombs, and suitcase bombs, as well as a search for "pistol on my lap," which lead to a page containing the image sent to the victims, according to court documents. 

Authorities have said they do not believe Stevenson had access to bomb-making materials or sarin gas. Extensive searches by police turned up no explosive devices. 

The suspect has been held in the Canyon County Jail on a $2 million bond since his March arrest. He was set to enter a guilty plea at a court hearing Tuesday, but Judge Davis Vandervelde ultimately elected to push back the plea change hearing to next month. 

Stevenson is due back in court Oct. 4.