One of the woman convicted in the notorious "Slender Man" knife attack in Wisconsin has gone missing after cutting off her monitoring bracelet.

The Madison Police Department says Morgan Geyser left a group home Saturday evening, having last been seen around Kroncke Drive at 8 p.m. "with an adult acquaintance."

Police were notified of her disappearance Sunday morning and have issued an appeal to anyone who sees her to call 911.

Geyser and Anissa Weier were 12-years-old when they stabbed classmate Payton Leutner 19 times in woods in Waukesha in 2014.

They told investigators that they carried out the attack to please Slender Man, a fantasy horror character that they believed to be real.

In 2017, Geyser reached a deal with prosecutors that she would enter a mental health facility for at l

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