The two juvenile girls accused of stabbing their classmate as a sacrifice to the online horror character Slender Man can be tried as adults, a Wisconsin appeals court ruled Wednesday.

The 2nd District Appeals court upheld a lower court's decision, although the girls can appeal to the Wisconsin Supreme Court. It was not immediately clear if their attorneys planned to do so, but have tried to keep their cases in the juvenile system moving to trial.

NBC News is withholding the identity of the girls because of their ages. They were both age 12 in May 2014 when prosecutors say they lured a third friend into the woods of the Milwaukee suburb of Waukesha the morning after a birthday sleepover. The suspects stabbed her 19 times with a knife, just missing an artery near her heart.

The victim was left to die, but managed to crawl away to safety. The girls later told police they wanted to kill their classmate as a way to appease Slender Man, a faceless meme on the internet.

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One of the girls, now age 13, has been receiving treatment at a state mental hospital, while the other, now 14, has been at a juvenile detention center.

They have been charged with attempted first-degree intentional homicide. If found guilty as juveniles, they could receive up to three years behind bars with supervised released when they are 18. But they face up to 45 years in prison if they are convicted as adults.