One of two girls accused of brutally stabbing a classmate in the woods of southeastern Wisconsin was obsessed with the fictional character Slender Man — stashing more than 60 drawings of the bogeyman meme and hoarding mutilated Barbie dolls inside her bedroom, a court heard in testimony Tuesday.

The disturbing details from an investigator were part of a preliminary hearing in which a Waukesha County Circuit Court judge heard evidence for a second day, reported NBC affiliate TMJ. The judge will ultimately decide whether to order a trial against the two girls as adults. The suspects — who could be tried for attempted first-degree intentional homicide — were 12 at the time of the near-fatal attack last May, although one of them has since turned 13. The judge said he would make a decision March 13.

In addition to the 12-year-old girl's Slender Man obsession, she still holds an "unyielding" belief in him, a child psychologist who interviewed her after the stabbing also testified Tuesday.

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The psychologist, Deborah Collins, said the girl had claimed that the Vulcan mind meld from "Star Trek" was real and that she could see "Harry Potter" characters.

The judge previously ruled that both accused girls are competent enough to stand trial after they underwent psychological evaluations and counseling. But a lawyer for one of the girls argued Monday during the first part of the hearing that his client should be charged as a juvenile. The lawyer said the child thought she had to kill her classmate for Slender Man or else, the girl believed, the character would kill her family.

NBC News is not identifying the girls because of their ages. If tried as adults and convicted, they each face up to 60 years in prison. The 12-year-old victim, meanwhile, has physically recovered after she was stabbed 19 times all over her body and left for dead.

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Turns out #HBO is part of the media pool this morning, monitoring the #SlenderManStabbing suspect case. @tmj4 — Julia Fello (@JuliaFello) February 17, 2015

Defense attorney showing multiple drawings of what appears to be #SlenderMan in suit w/hollow eyes & another image holding a knife @tmj4 — Julia Fello (@JuliaFello) February 17, 2015

— Erik Ortiz