A threatening note found at an Illinois high school this week, reading “this school is going down today,” was left by one of the teachers, federal and state authorities alleged.

Michelle Lynn Smith, 36, is accused in federal court of typing a letter that said, “KABOOM!!!!!!!!!!!!!! Im tired of all the people here. Everyone is going down, the school will b n flames.”

Smith, a teacher at Calhoun County High School in Hardin, was being held without bond on a charge of conveying a false threat. She’s scheduled to appear in court Monday for a detention hearing. If convicted, she faces up to five years in federal prison.

The letter -- filled with misspellings, abbreviations and grammatical mistakes -- suggested that its writer was fed up with colleagues, who were described as doing nothing to help others and showing favoritism among their ranks. The high school has 171 students, according to state data, and about 20 faculty members listed on its website.

“If I had certain names I would not have the truble I do,” the letter said. “Don’t matter, this place sucks and will not be here for long. So long and GOOD-BYE!!!!!!!!!”

After the note was spotted in a women’s restroom at the school, authorities called for an evacuation and swept the building but found no explosives. Police have not said what led them to Smith as the suspect.

“Actions such as these cause not only massive wastes of law enforcement resources, but strike fear into the hearts of parents and students alike,” Stephen Wigginton, the U.S. attorney for the Southern District of Illinois, said in a statement. “Because children should feel safe in their schools, we take these charges very seriously.”

Smith was initially arrested Tuesday and charged in state court on a count of falsely making a terrorist threat.

State education records show Smith was a special-education teacher who graduated from Southern Illinois University-Carbondale. The 13-year veteran is on paid administrative leave, pending review of her case by the school board.

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