Slender Man stabbing: Teen sentenced

One imagining of Slender Man.
One imagining of Slender Man. Photo credit: Getty

A teenager who tried to kill a classmate to impress a fictional character known as 'Slender Man' has been sentenced to 25 years in a psychiatric hospital.

Anissa Weier, now 16, and Morgan Geyser lured their classmate to a park in Milwaukee in 2014 and stabbed their victim 19 times. Geyser reportedly did most of the actual stabbing, while Weier cheered her on.

Weier reached a plea deal in August, pleading guilty to being a party to attempted second-degree intentional homicide, but was found not guilty by reason of mental illness.

The pair said they carried out the stabbing to placate the fictional supernatural character 'Slender Man'.

"I do hold myself accountable for this and that I will do whatever I have to do to make sure I don't get any sort of delusion or whatever again," Weier told the judge, prior to her sentence being revealed.

"I want everybody involved to know I deeply regret everything that happened that day. I know that nothing I say is going to make this right and nothing I say is going to fix what I broke."

Originating on an internet horror forum, Slender Man stories often revolved around matters of stalking, abduction and traumatisation.

The figure inspired video series Marble Hornets and first-person survival game Slender.

Both the girls were 12 at the time of the attack. The victim survived.

Weier will be 37 before she's eligible for release, the sentence beginning from the date of the attack.

Geyser, also found not guilty by reason of mental defect, is yet to learn how long she will be held. Prosecutors have asked for at least 40 years.