Two 13-year-old girls who were arrested for allegedly stabbing a fellow classmate to please online horror character "Slender Man "will stay in adult court, a judge in Wisconsin ruled on Monday. The judge reasoned that by keeping them in adult prison, people would be protected longer. He was also worried that both teenagers would stop getting mental health treatment and may not get proper supervision once they are released from the juvenile detention system and return to the community by the age of 18.

"The real issue is what happens in a few years. They've committed an offense that was frankly vicious," said Waukesha County Circuit Judge Michael Bohren, according to the Associated Press.

Morgan Geyser and Anissa Weier were arrested on May 31, 2014 for stabbing their now-former friend Payton Leutner 19 times after they lured her into the woods in their hometown of Waukesha and left her there fighting for her life. Leutner was discovered and rushed to the hospital. She sustained life threatening injuries, but managed to survive.

Geyser and Weier both admitted an obsession with "Slender Man," a fictional character often portrayed as a faceless, horror figure who stalks children in online fan fiction stories, prosecutors claimed. Geyser admitted to authorities that they began planning to kill their friend as early as December 2013.

Authorities also revealed that Geyser repeatedly told detectives that killing Leutner was "necessary" so that she and Weier would become "proxies" of "Slender Man" and live with his mansion they believe was located in the Chequamegon-Nicolet National Forest in northern Wisconsin, according to ABC News.

The teenagers were both 12 at the time when they committed the crime. Under Wisconsin law, anyone who is 10-years-old or older charged with first-degree attempted homicide is automatically considered an adult.

If convicted as adults, both could each face up to 65 years of prison. The juvenile system, on the other hand, is geared more towards the rehabilitation of juveniles than punishment and the teens would only spend five years in the system, according to FOX News.