'Slenderman' stabbing suspect believed character would kill family if she did not murder friend: attorney Anissa Weier, now 13, told police she feared the fictional Internet character would 'kill my whole family in three seconds' if she and friend Morgan Geyser, 12, did not follow through on a deal to kill their best friend since the fourth grade. Their attorneys argued in a preliminary hearing Monday that the middle schoolers should be charged as juveniles. BY Rachelle Blidner NEW YORK DAILY NEWS Morgan Geyser,12, stabbed her friend because she believed Slenderman could kill her, defense attorneys said. One of two Wisconsin middle schoolers accused of stabbing their friend believed the Internet character Slenderman would kill her whole family if she did not kill the girl, her attorney told a Waukesha judge Monday. Anissa Weier, 13, and friend Morgan Geyser, 12, made a deal with the paranormal figure that "their families would be in danger" if they did not murder Peyton Leutner, 12, Waukesha Police Detective Michelle Trussoni said during a preliminary hearing Monday, according to Fox 6. Weier told police she feared Slenderman's wrath after reading online horror stories about the faceless creature, said to be 6 to 14 feet tall. She also said she wanted to prove he was real. "He targets children most, so I was really scared knowing that Slenderman could easily kill my whole family in three seconds," Weier said in an interrogation video obtained by ABC News. To appease Slenderman, Weier and Geyser stabbed their friend 19 times in the woods during a game of hide-and-seek in May, prosecutors said. Geyser whispered, “I’m so sorry,” to the victim right before stabbing her, Officer Shelly Fischer said. Anissa Weier, now 13, said she was afraid Slenderman would kill her ‘whole family in three seconds’ if she did not murder her friend. Enlarge Morgan Geyser, 12, showed no remorse after the killing, police said. Enlarge Leutner survived and turned 13 Friday, according a Facebook post. Prosecutors presented passages from Geyser’s notebook, including a plot supply list that included the “will to live.” Other excerpts said, “he still sees you” and “safer dead.” Geyser showed no remorse for the crime, Wausheka Detective Tom Casey said. Weier and Geyser blamed each other for the murder plot, claiming the other had come up with the idea five months before the stabbing, the Milwaukee Journal Sentinel reported. The girls initially planned to stab Leutner in her sleep during a slumber party but changed their minds in the middle of the night, Trussoni told the judge. They then abandoned a second idea to kill her in a park restroom to flush blood down the drain, she said. The middle school suspects are being charged with first-degree attempted homicide as adults. Their attorneys argued they should be charged in children's court Monday. A judge will decide Tuesday whether the girls will be charged as adults or juveniles. If tried as adults, the girls could spend up to 60 years in prison. If charged as juveniles, they could be released by age 25. The preliminary hearing was postponed after Geyser was declared mentally incompetent in July. She was declared fit to stand trial in November.