The two young Wisconsin girls pleaded not guilty to first-degree attempted murder charges on Friday for allegedly stabbing their 12-year-old friend multiple times after being influenced by a dark fictional character named "Slender Man."

A Wisconsin court entered not guilty pleas on behalf of Anissa Weier and Morgan Geyser, who are both 13 years old, in the infamous "Slender Man" case, reports ABC News.

Back when the suspects were just 12 years old, they allegedly spent months plotting to kill their friend Payton Leutner, who was also 12 at the time, in order to please Slender Man. They then lured Leutner into a southeastern Wisconsin park after a sleepover and stabbed her 19 times in May 2014.

After Leutner was presumably left for dead, she managed to crawl out of the woods and was discovered by a bicyclist who called 911. She miraculously made a full recovery.

Meanwhile, the suspects were found walking toward a national forest where they said they believed Slender Man lived in a mansion. They told investigators they decided to kill Leutner as a sacrifice in order to win favor with the figure.

Prosecutors said the girls were obsessed with Slender Man, who is depicted in online horror stories as a faceless man who kidnaps and kills children. Authorities also said that Geyser told detectives that they wanted to become "proxies" of Slender Man, and to do so, it was "necessary" for them to kill Leutner.

On Friday, Judge Michael O. Bohren stated that Weier and Geyser will be tried together in an adult court starting Oct. 15. If convicted, the girls could each face up to 65 years in prison.

Prior to Friday's hearing, defense attorney Tony Cotton, who represents one of the girls, announced that his client would enter a not guilty plea by reason of mental disease or defect, reports NBC News.