Two girls accused of stabbing a classmate in a southeastern Wisconsin park to please a fantasy character called Slender Man will find out this week whether they will be tried on attempted homicide charges.

A preliminary hearing for the two Waukesha girls is set to begin Monday in Waukesha County Circuit Court, with a judge to decide if there's enough evidence to order a trial.

Prosecutors charged the girls as adults with first-degree attempted homicide in the attack last May, and each could be sentenced to up to 60 years in prison, if tried and convicted.

Preliminary hearings are often formalities but can sometimes become mini-trials complete with witness testimony. Judge Michael Bohren has set aside Monday and Tuesday for the hearing, suggesting it could be extensive. Court records indicate that prosecutors plan to call four witnesses, including a detective, on Monday. Questions for them are expected to consume the entire day.

Bohren ruled that the alleged attackers are competent to stand trial in December. The Associated Press isn't naming them because their attorneys have said they may still seek to move their cases into juvenile court, where proceedings are secret.

Neither girl's attorney, Tony Cotton and Joseph Smith Jr., nor the head prosecutor, Assistant District Attorney Ted Szczupakiewicz, responded to phone messages Friday seeking comment.

Janine Geske, a Marquette University law professor and former Wisconsin Supreme Court justice who is not involved in the case, said the defense attorneys know their clients almost certainly will have to stand trial.

They'll try to use the proceedings to learn more about the prosecution's tactics, she said. They'll also likely try to elicit testimony that could support potential insanity pleas. If a detective, for example, talks about how the girls felt they were in a fantasy world, it would bolster an insanity case and support motions to suppress the girls' statements to police, Geske said.

"It's an opportunity to find out where the case is," she said.

Wendy Murphy, a former Massachusetts prosecutor who teaches law at New England Law-Boston, said the fact that the hearing has been scheduled for two days suggests that the defense lawyers may have as-yet undisclosed evidence they want to present in the hopes of influencing the judge or potential jurors through media coverage.

"They might be using the high-profile nature of the proceeding to continue to build a narrative in the court of public opinion," said Murphy, who also isn't involved in the case. "The defense could have information that we haven't heard yet that they want to play out in sort of a trial balloon sense. What would the public reaction be to new information about motive and so forth?"

According to court documents, the girls had been planning to kill the victim for months to curry favor with the fictional Slender Man, discussing their scheme using code words. They lured the girl to a wooded Waukesha park where she was stabbed 19 times. It's unclear from the documents who did the stabbing. One of the girls said the other did it; that girl said they both did it.

The girls left the victim bleeding in the woods, according to prosecutors. She crawled to a sidewalk where a bicyclist found her and called 911. The two girls accused of attacking her were found walking toward the Nicolet National Forest where they say they thought they would join Slender Man in his mansion. Police found two knives on the girls.

All the girls were 12 at the time of the incident. One of the girls accused in the stabbing has since turned 13.