The two Wisconsin tween girls accused of stabbing a friend 19 times and leaving her in a park—because they believed doing so would protect their families from the mythical internet horror known as Slender Man—will be tried as adults for first-degree attempted homicide, a judge ruled Friday.

The girls were 12 at the time of the incident, as was the victim, who ultimately survived the attack.

Their attorneys claimed the girls' apparently sincere devotion to Slender Man—a gaunt, creepy figure with long arms and a blank face—was a mitigating factor that should have lessened the charge to second-degree attempted homicide, the AP reported. That could have kept the trial in juvenile court—the first-degree offense must be tried in the adult system.

Prosecutors say the killing was premeditated, and the two only stabbed their friend after formulating a months-long plot to kill her. The teens said they believed they would be able run away to Slender Man's mansion in the woods, where they would live as the demon's "proxies."

Police picked them up in Wisconsin's Nicolet National Forest, where they were allegedly searching for Slender Man's home.

One of the two girls was initially found mentally unfit to stand trial as a result of her Slender Man delusions, but that decision was later reversed after psychologists found her mental condition had "improved."

Both girls' attorneys have requested hearings to argue the case should be moved back to the juvenile system. Those will take place in May and June.

If convicted of first-degree attempted homicide, they face up to 60 years in prison.

[Photo: AP Images]