A teenager who pleaded guilty to sending threatening social media messages in March that led to extra security at Red Wing schools was sentenced Wednesday to five years probation and 120 hours of community service.

Keyah Mykah Mizer, 18, was sentenced Oct. 10, 2018, on one count of felony threats of violence. She was given a stay of imposition, meaning the conviction will be deemed a misdemeanour upon successful completion of probation. Terms of the probation include no contact with victims and no abusive or threatening behavior.

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Defense attorney John Gavin argued for a stay of adjudication, in which the conviction would not appear on Mizer's criminal record if conditions were met. A presentence investigator recommended the stay of adjudication, something Gavin said he has rarely seen in his years as a public defender. Though prosecuting attorney Christopher Schrader objected, citing the impact of the threats on the community, school district and students.

Judge Kevin Mark said he had to accept the state's objection to the stay of adjudication, but offered words of sympathy to Mizer, saying everyone makes mistakes.

"If there's one life lesson that comes out of all this, it's not to respond to negative, destructive actions with negative, destructive actions," Mark said Wednesday.

Fighting back tears, Mizer told the court she wakes up daily thinking about the burden her actions have placed on her family, friends and community.

"It's definitely been the biggest mistake of my life," she said.

Mizer was arrested March 22 after investigators determined she had sent threatening messages to herself and two others using a spoofed phone number the day before. The threats, made a week after Red Wing students walked out of class to honor 17 people killed in a school shooting in Parkland, Fla., prompted an increased police presence at the high school and indoor recess at other area schools.

Mizer pleaded guilty to the threat charge in July. Charges of falsely reporting a crime and disorderly conduct were dismissed.

The judge suggested the 120 community service hours could include Mizer giving positive advice to other young people.