Two 13-year-old Wisconsin girls accused of luring their friend into some woods to repeatedly stab her as a sacrifice to a fictitious horror character pleaded not guilty Friday.

The teens from the Milwaukee suburb of Waukesha are being tried as adults and face decades in prison if they are convicted in the 2014 attack.

A judge entered not guilty pleas on behalf of both girls at a brief arraignment hearing Friday.

Investigators have said the two plotted for months to lure their friend Payton Leutner into the woods after a sleepover. They intended to kill her, police say, to win the favor of Slender Man, described as an unnaturally tall and thin man who wears a dark suit and has no visible facial features. Slender Man stories have proliferated online in recent years.

They wanted to kill for him, in part, to prove his existence, police documents allege.

The girls, 12 at the time of the stabbing, believed they would have a home in Slender Man's mansion if they carried out the attack, police say.

After stabbing their friend and leaving her for dead, the girls started walking to a forest 300 miles away, where they believed he lived, according to police documents.

Payton suffered 19 stab wounds, including one that doctors say narrowly missed a major artery near her heart. After the attack in a wooded park, she crawled to a road and was found lying on a sidewalk by a passing bicyclist. Despite the attack, she staged what her family called a "miraculous" recovery and was back in school in September, three months after the attack.

Tony Cotton, an attorney for one of the girls, said ahead of the hearing that she would enter a plea of not guilty and not guilty by reason of mental disease or defect. The other girl's attorney did not respond to requests for comment.

Defense attorneys have argued that the case belongs in juvenile court, saying the adolescents suffer from mental illness and won't get the treatment they need in the adult prison system.

But Waukesha County Circuit Judge Michael Bohren decided this month that the girls should be tried in adult court, despite their age, saying if they were found guilty in the juvenile system they would be released at 18 years of age with no supervision or mental health treatment. Keeping them in the adult system would protect them longer, he said.

They each face a charge of attempted first-degree intentional homicide.

The Associated Press has not identified the girls because an appeals court could move their cases to juvenile court, where proceedings are closed.

The girls face 65 years in prison if convicted as adults. They have been in custody since being arrested the day of the attack.