Anissa Weier is brought into court for a hearing last month. On Thursday, her attorney said she would plead not guilty by reason of mental disease or defect in the Slender Man case. She and Morgan Geyser are accused of stabbing another girl. (Photo: Michael Sears / Milwaukee Journal Sentinel) 
 
 Anissa Weier plans to enter a plea of not guilty by reason of mental disease or defect in the Slender Man stabbing case next week. 
 
 Weier's co-defendant, Morgan Geyser, had already entered such a plea, often referred to as NGI, at a hearing last month. 
 
 At the time, prosecutors pressed the judge to inquire whether Weier might go the same route, since it requires the court to appoint doctors to examine the defendant and report whether their condition would support the plea. One of Weier's attorneys, Maura McMahon, said the defense had not yet decided. 
 
 But in a pleading filed this week, McMahon indicated that Weier now wants to change her not guilty plea to the insanity plea. A hearing was set for Sept. 9 for that change of plea. 
 
 Weier and Geyser, both 14, were 12 when prosecutors say they plotted and attempted to kill their sixth-grade classmate and friend Payton Leutner in May 2014. 
 
 ARCHIVE: Slender Man case coverage 
 
 Leutner was stabbed 19 times and left for dead in a Waukesha park the morning after a sleepover party for Geyser's 12th birthday, but managed to crawl near a path, where she was found by a passing bicyclist. 
 
 Both defendants later told police they were trying to either impress or avoid the wrath of Slender Man, a fictional internet boogeyman the girls said they believed would harm them or their families if they didn't kill their friend. 
 
 They remain charged as adults with attempted first-degree intentional homicide, after efforts to have their cases transferred to juvenile court were denied. 
 
 A defendant entering an NGI plea contends that at the time she committed a crime, a mental disease or defect prevented her from appreciating the wrongfulness of her action, or from conforming her conduct to the law. 
 
 Someone found not guilty by reason of mental disease or defect is typically committed to a state mental hospital for treatment. 
 
 Geyser, who has been diagnosed with early onset schizophrenia, has already spent months at Winnebago Mental Health Institute under a separate civil commitment. 
 
 During earlier hearings, mental health experts testified that Weier was competent to proceed with the case, but had not done more extensive evaluations required for an NGI review. She remains at a West Bend juvenile detention center. 
 
 No trial date has been set in the case. 
 
 Read or Share this story: http://on.jsonl.in/2civi3X ||||| Two girls accused of trying to kill a classmate to please horror character Slender Man want jurors from outside their home county to decide their trials. 
 
 
 
 Morgan Geyser's attorneys filed a motion this week seeking jurors from outside Waukesha County because of heavy media coverage. Geyser has pleaded not guilty by reason of mental disease or defect. 
 
 
 
 A letter the other girl's defense attorneys submitted to the court seeks outside jurors as well. The letter noted that girl plans to plead not guilty by reason of mental disease or defect. 
 
 
 
 Investigators say Geyser and Anissa Weier, who were 12 at the time of the 2014 attack, plotted for months before luring the victim, who also was 12, into some woods and repeatedly stabbing her. The girls hoped killing her would please Slender Man, a demon-like character in online stories. 
 
 
 
 The victim crawled out of the woods to get help. 
 
 Both girls face an attempted homicide charge in adult court. Their attorneys had been fighting to move them into juvenile court but a state appeals court in July ruled they should remain in adult court.
– Both girls in Wisconsin's disturbing "Slender Man" case will now be pleading not guilty by reason of insanity. Attorneys for 14-year-old Anissa Weier signaled this week that they want to change her plea in the attempted murder case from not guilty to "NGI," meaning that she's likely to be committed to a state mental hospital for treatment if found not guilty, reports the Milwaukee Journal Sentinel reports. Co-accused Morgan Geyser, who is also 14, has been diagnosed with early onset schizophrenia and has already entered an NGI plea. Both girls were 12 years old in 2014 when they allegedly stabbed a 12-year-old classmate 19 times and left her for dead in what they told investigators was an attempt to please the online horror character "Slender Man." In July, an appeals court ruled that they should be tried as adults for the attempted killing. WISN reports that lawyers for both girls are seeking to have the case heard by jurors from outside Waukesha County, where the attack took place, because of heavy media coverage.