Investigators say 22-year-old Grant Stevenson has a history of making bomb threats against Idaho schools.

CALDWELL, Idaho — A Nampa man arrested on terrorism charges Thursday night had vowed to release a deadly nerve agent and set off a series of car bombs at a Nampa apartment complex, according to court documents.

Grant Charles Stevenson, 22, faces felony charges of terrorism and threatening to use weapons of mass destruction, as well as two misdemeanors for using a telephone to harass someone.

The investigation began at 4:14 p.m. Thursday when police say Stevenson - using a fake Facebook account with the name "Tony Abdul" - sent a series of alarming messages to the Nampa Police Department Facebook.

According to the probable cause affidavit filed in the case, the first message indicated that a bomb containing sarin gas - an extremely toxic compound used in chemical warfare - had been planted in one of the units in an apartment complex on South Juniper Street.

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The sarin attack was set to occur in one hour, the message read, along with five additional car bombs.

"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."

In two subsequent messages, police say, Stevenson seemed to link the attack to the Islamic State, writing "death to America" and the "the calphite (sic) will prevail."

The threats touched off a massive law enforcement response, with Nampa Police, the FBI, ATF, and the National Guard mobilizing along with paramedics, Nampa Fire and a HazMat team.

Because of the threat of sarin gas exposure, Skyview High School, Northwest Nazarene University and Nampa Recreation Center were all placed on a lockdown that stretched on for six hours. The police department also sent out alerts to people living in the area, asking them to shelter inside their homes and not go outside while authorities investigated the "unsubstantiated bomb threat."

Investigators zeroed in on Stevenson as a suspect after a tipster called Nampa Police to tell them that Stevenson had made fake bomb threats as a teenager, and might be connected to the Nampa threat. The tipster also told police that Stevenson was angry at a woman who lived in the area where the sarin bomb was reported.

According to the probable cause affidavit, Stevenson was arrested in 2013 for making a string of bomb threats to schools in Boise, Caldwell, Nampa, Kuna and Twin Falls.

Police learned that both the woman Stevenson was angry at and her boyfriend had also received threatening messages from the "Tony Abdul" Facebook account at about 4 p.m. that day.

Both victims were sent a picture of a person sitting in a car with a gun on his lap, police say. In the message to the female victim, the sender threatened to kill her boyfriend and show up at her house that night or the next day, writing "please don't make me rape u," according to court documents.

In an interview, Stevenson denied being behind the messages but told police he had expected them to come talk to him because of his history with false bomb threats.

The suspect agreed to allow detectives to search his phone, but when police asked him to take a polygraph test, said he wanted to speak to a lawyer.

According to the probable cause affidavit, the officers found Google searches for pipe bombs, car bombs and suitcase bombs on Stevenson's phone, as well as an image search for "pistol in my lap," which led to a page containing the same photo sent to the victims.

Stevenson was arrested and booked into the Canyon County Jail.

Nampa Police say that despite the threats, Stevenson had no actual access to bombs, bomb-making materials or nerve gas. Likewise, investigators have found no link between Stevenson and the Islamic State.

Nevertheless, the prosecutor at Stevenson's first appearance Friday urged Judge Thomas Sullivan to set Stevenson's bond at $5 million, pointing to the massive police response and the panic caused by the threat.

"The level of threat - this type of thing descends a society into chaos," the prosecutor argued.

The suspect's public defender petitioned for "something more reasonable," arguing that a $5 million bond was far too high.

Stevenson, who appeared via video conference in an orange jail uniform, repeatedly wiped tears from his face during the brief arraignment.

The judge ultimately set bond at $2 million, ordering that Stevenson have no contact with the victims or the tipster who called Nampa Police, and that he be GPS monitored if he is able to post bond.