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PITTSBURGH (KDKA) — A former student at Keystone Oaks is facing serious charges after police said he threatened to kill several former classmates and hide a bomb in the school.

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Matthew Dobos, 19, is facing charges that include making terroristic threats and witness intimidation.

(Source: Allegheny County)

Detectives said he used the public computers at The Carnegie Library in Squirrel Hill to send death threats via Facebook to at least six Keystone Oaks students.

Police said the messages included: “See you in school tomorrow. I’m placing a bomb there,” “I will kill you” and “I will blow up KO.”

Detectives said he also used the library’s phone in early January to call 911 and report that a man in a red hoodie with a gun in his waist band was standing near the Squirrel Hill News Stand.

When officers swarmed the area, they found Dobos standing there in a red hoodie.

When asked why he would call in a gun threat where he was the suspect, he told police he was “mentally handicapped.”

The incident sparked the investigation that led to his arrest.

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KDKA took Dobos’ mugshot to the Squirrel Hill News Stand to see if they’d ever seen him before.

“Matt! That’s Matt!” said Debbie Mozumder, an employee. “He was very nice to me and I don’t know why he did all this thing, I’m shocked. I’m totally shocked.”

Mozumder said Dobos would come into the store regularly and “acted like a kid.”

“I know that he always used to go to the library, because after the library, he used to come here and tell me, ‘I was in library, Debbie,’ and I was like ‘Okay,'” she said.

She said she remembered the day last month when police entered the store out of the blue and asked the clerks if they’d seen a man with a gun.

“All of a sudden four cops came in and one was here looking at the magazines and they were scattered,” said Mozumder. “We just heard from cops, ‘Is there anybody here with a gun? Did you see anybody?’ and we said, ‘No.'”

She said she didn’t put the details together until she saw his mugshot. She said he’s been noticeably absent and she had wondered where he’d been.

keystone oaks high school

(Photo Credit: KDKA)

Keystone Oaks cancelled class on Monday for a separate threat posted online by a suspect. Police have not yet released the name of that suspect, but it appears to be a separate incident.

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Police said Dobos was living in a group home in Squirrel Hill. He is now in the Allegheny County Jail.

Meghan Schiller