Homeland Security says Dae Woong Lee, a 20-year-old South Korean national, living in Seoul, made the prank call that harassed the Hackettstown (N.J.) School District in March 2012.
For Bennett Rymon, answering that call at the Warren County, N.J., 9-1-1 center turned a typical March day into madness.
"Said he was going to shoot kids. Wanted to shoot kids," Rymon said.
This set off a firestorm of fury as police swarmed Hackettstown High School.
"You don't think of anything other than getting everyone locked down and safe," Vice Principal Roy Huchel said.
But police say the call was a hoax, made by Lee, a then-19-year-old member of the South Korean military.
Using the alias Keven McGowen, Lee said he had an AK-47, was going to shoot students, one in particular. The call was dialed all the way from Seoul, South Korea.
Sayaka Ogawa was a senior at the time.
"I don't really understand how he came in contact with Hackettstown, but it's scary," Ogawa said.
Investigators say Lee met a female Hackettstown High student on a social media website.
It's still not known why Lee made the threats, but Rymon, who spoke to Lee for over an hour, said the South Korean told him he was upset he broke up with his girlfriend.
"It's scary somebody so far away could threaten our school like that," Ogawa said.
The phone number police said couldn't be initially traced. But leads led Homeland Security to South Korea, where their government questioned Lee in January, then arrested him in June, charging Lee with obstruction of business.
Warren County warns all would-be pranksters, local or worldwide, it's a practice that won't go unpunished.
"Message should be we are not going to tolerate it and people should think twice," Warren County Prosecutor Richard Burke promised.
Lee could face up to five years in prison and the equivalent of a $15,000 fine.
Officials say Lee won't be extradited to the U.S.