CALDWELL, Idaho — A man's hoax about releasing a deadly nerve agent in a Nampa neighborhood is landing him in prison. 

Grant Stevenson, 22, was sentenced Monday to 15 years behind bars. He will have to serve at least three years of that sentence before he can become eligible for parole, a judge ruled.

The sentence came as part of a plea deal that saw Stevenson plead guilty to a felony count of committing terrorist acts. Prosecutors dropped additional charges of telephone harassment and threatening to use weapons of mass destruction. 

Stevenson was arrested in March after sending a message to the Nampa Police Facebook page under a fake name, in which he wrote "death to America" and warned of car bombs and an explosive containing sarin gas set to go off in the city.

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Prosecutors say Stevenson's hoax was targeting a woman who lived in an apartment complex where he had reported a bomb. That woman and her boyfriend also received threats from the same fake profile that messaged Nampa Police. 

The threat spurred six-hour lockdowns at Skyview High School, Northwest Nazarene University and Nampa Recreation Center. Local police and paramedics mobilized along with the FBI, ATF, and the National Guard until authorities could confirm that the threat was a hoax. 

Prosecutor Bryan Taylor argued in court that anything less than prison would diminish the seriousness of the crime and the terror Stevenson had sowed with his threats. 

"People come to Canyon County to live because it is safe and secure," he said. 

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The prosecutor also noted that the March incident was not the first time Stevenson called in a fake bomb threat. As a teenager, he made repeated false bomb threats at area schools, and ultimately spent three years in juvenile detention for it, Taylor said. 

A 15-year sentence would "send a message to [Stevenson] that this is not acceptable behavior," Taylor argued.

Stevenson's lawyer, Peter Mommer, asked Judge Davis VanderVelde to stick to the plea agreement, noting that the hoax was ultimately "a non-violent offense."  

"He's here to accept responsibility today," Mommer said. "He knows what he did caused a lot of panic in the community, and he's sorry for that."

Although Stevenson declined to speak in court before his sentence was handed down, his lawyer said he had written a letter to the judge about his motivations. 

In addition to the prison sentence, VanderVelde ordered Stevenson to pay nearly $10,000 in restitution for the emergency response he had sparked. The judge said he hoped Stevenson used his time in incarceration to change himself. 

"I hope that you will take this time to better yourself so you can return to our community and be a productive member of society," VanderVelde said.