A JUDGE has sentenced a 15-year-old girl to the maximum 40 years in a mental hospital for stabbing a classmate in an attack aimed at pleasing a fictional horror character known as Slender Man.

Judge Michael Bohren said Morgan Geyser, one of two Wisconsin girls who attacked their friend, remained a risk to hurt herself or others.

Bohren said in passing sentence on Thursday that although the attack happened when the girls were young, “what we can’t forget is this was an attempted murder.” Geyser spoke briefly before she was sentenced, breaking down in tears as she apologised to the girl she stabbed. That girl survived.

Earlier, doctors who examined Geyser have provided conflicting opinions about the type of institutional care she needs.

Dr Brooke Lundbohm says the teenager’s mental health has improved, but that she should continue being treated at a state mental health facility. Lundbohm said Geyser is still a danger to herself and others, and has reported hearing voices as recently as September.

Two other doctors at the sentencing hearing said Geyser no longer exhibits psychotic symptoms and recommend moving her to a less restrictive facility where she can be around others her age and possibly go out with supervision.

Meanwhile, the mothers of Weier and Geyer insisted there were no warning signs their kids were ever mentally ill — or possibly murderous.

Angie Geyser and Kristi Weier told ABC News they couldn’t believe their daughters were capable of carrying out such a violent attack.

“I never would have imagined that my daughter was capable of hurting another person,” Angie Geyser told the outlet.

In 2014, when Morgan and Anissa were 12, they hatched a plan to kill their friend Payton Leutner, also 12 at the time. The girls were intending to appease the online fictional character “Slender Man,” a shadowy figure that’s often depicted in fan fiction stories as a horror figure who stalks children. Morgan and Anissa were obsessed with “Slender Man” and plotted the attack on Payton for more than five months, later telling investigators “it was necessary” to please “Slender Man”, reports the New York Post.
On the morning of May 31, 2014, Anissa, Morgan and Payton were waking up from a birthday sleepover party at Morgan’s house. The girls asked Geyser if they could go to the park, and she had no idea anything was wrong until police knocked on her door.

“I was vacuuming in the basement and my son, who was six at the time, came downstairs and he told me that the police are here, and they’re looking for Morgan,” Geyser said.

“Of course, my heart dropped down into my stomach and I went upstairs. Not only were there police in my living room, but they were wearing riot gear.”

“They asked me, ‘Where’s Morgan?’ I said, ‘She’s at the park with her friends,’” the mother explained.

The police didn’t believe her and started searching the house, thinking she was hiding Morgan.

“I just kept asking, ‘What happened, what’s going on,’ and they wouldn’t tell me other than to say there had been an incident in the park and one of the girls was hurt,” Geyser said.

Little did she know, her daughter had savagely attacked Payton in the woods with a kitchen knife, stabbing the pre-teen 19 times while Anissa urged her on, investigators said.

“Morgan hands me the knife and says, ‘I can’t do it, you know where all the soft spots are,’” Anissa told police while they were interrogating her.

“And then I give it back to her and say, ‘You do it … Go ballistic. Go crazy. Make sure she’s down’ … Morgan said, ‘I’m not doing it until you tell me to.’ I started walking away and then, like, when I was 5 feet (1.5 metres) away I said, ‘Now’.”

Morgan admitted to police that was the moment she started stabbing Payton repeatedly. The police then asked Morgan what she did with the knife she used.

“I put it back in the bag and walked,” Morgan told police.

“I sort of wiped it off on my jacket. It was weird. I felt no remorse.”

The girls left Payton, now 15, for dead, but she crawled out of the woods and got help from a passing bicyclist. She miraculously survived the attack.

Morgan’s mother said it was extremely hard to watch the interrogation.

“That’s not my daughter saying those things,” she said. “That’s not the way she speaks. That’s not the way she acts.”

“She appears to have no remorse for what’s happened, and she just talks about it in such a flat manner,” Geyser continued.

“That’s odd for a 12-year-old child sitting in a police station with a detective, not to be frightened about what’s going on.”

Weir said her daughter Anissa had never discussed “Slender Man” with her, and she kept a watchful eye on her young daughter.

“[Anissa’s father] and I, although we were divorced, we were still very active parents. I did search her iPad. I did watch over her shoulder,” Weier said.

“Anissa never talked about Slender Man to me.”

Morgan’s mother said she could never imagine her daughter committing such an atrocity.

“They [Morgan and Payton] would sit up in Morgan’s room and they would do each other’s nails, and they would laugh, and make a mess,” Angie Geyser said. “They were just typical girls.”

While incarcerated, Morgan was diagnosed with early onset schizophrenia, which was not a surprise to the family because Morgan’s dad has schizophrenia. The illness tends to run in families and is often passed down from parent to child.

Dr Melissa Westendorf, the court-appointed forensic psychologist on the case, said Anissa was diagnosed with a “shared psychotic disorder” and said Morgan’s schizophrenia, coupled with both girls’ delusions about Slender Man, created a perfect storm.

Anissa, now 16, pleaded guilty last year to attempted second-degree intentional homicide, as a party to a crime, with the use of a dangerous weapon as part of a plea deal. A jury later found her not guilty by reason of mental disease or defect and she was committed to a mental health institution for 25 years.

Earlier this year, Morgan, now 15, pleaded guilty to attempted first-degree intentional homicide. As part of a plea deal, the court also found Morgan not guilty by reason of mental disease or defect despite her earlier guilty plea. She will learn how many years she will have to live in a mental institution during a daylong sentencing scheduled for Thursday.