Slenderman trial: Lawyers attempt to show jury Anissa Weier was delusional

WAUKESHA -- A Waukesha County jury learned on Wednesday, September 13th about the first interviews after the vicious stabbing of a 12-year-old girl. This, in the so-called Slenderman trial of Anissa Weier.

Weier's lawyers are trying to show the jury that Weier was delusional when she was involved in the stabbing of a classmate -- stabbed 19 times three years ago for Slenderman. The jury on Wednesday watched parts of Weier's confession video, where it was Weier who told Morgan Geyser to do it.

"We are talking about the intersection between mental health, adolescent development and technology," Maura McMahon, Weier's defense attorney said.

Anissa Weier

"Go ballistic. Go crazy. Make sure she's down," Weier says in the confession video.

Then in the video, Weier said she walked away.

Anissa Weier

Did Weier actually believe she had to kill her friend because she believed Slenderman was real? The prosecutor questioned an investigator.

"Did she specifically tell you in response to a question, 'does it worry you you won't see Slenderman' or 'do you think he doesn't exist?' Response. 'He does not exist.' Did that happen?" questioned Waukesha County Assistant District Attorney Kevin Osborne.

"Yes," the investigator said.

"And you said 'OK'-- and she said 'he is a work of fiction,'" Osborne said.

Prosecutors argue Weier ultimately knew Slenderman wasn't real, and that she was desperate to maintain her friendship with Geyser.

"Anissa said that she didn't want Morgan to feel crazy, so she said 'yes.' That's what she said," Osborne said.

Waukesha police investigate stabbing incident

Waukesha police investigate stabbing incident

But a psychologist who reviewed the evidence and did interviews diagnosed Weier with a shared psychotic disorder, playing off of the psychosis of her friend, Morgan Geyser.

"What they had in common was the delusion about Slenderman, what they needed to do to go to Slender mansion and all of the characters and all of the characters associated with Slenderman," said psychologist Melissa Westendorf.

Two other psychologists are expected to testify that they also believe Weier suffered from a mental disorder.

If the jury agrees, Weier will go to a treatment facility instead of prison.