WAUKESHA, Wis. » A 12-year-old Wisconsin girl who was stabbed 19 times by classmates trying to please a fictional horror character had feared the specter known as Slender Man before the attack, her mother said in an interview aired Friday night.

Payton Leutner was attacked in a wooded park in late May following a sleepover to celebrate her best friend’s 12th birthday. Police say her friend and another 12-year-old classmate later told investigators they spent months planning the attack intended to win favor with Slender Man, the star of numerous spooky stories posted online.

Payton’s mother, Stacie Leutner, said her daughter asked about Slender Man before the attack because stories shared by her friend frightened her. Payton insisted her best friend knew Slender Man was real. Leutner was not overly concerned.

"Fantasy when you are 12 years old is still a very active part of your life," she said.

Leutner and her husband spoke with ABC’s David Muir for the season premiere of "20/20." It was their first interview since the May 31 attack in Waukesha County, west of Milwaukee. Muir went school shopping and to an animal shelter with Payton but did not ask her about the attack and she did not speak on camera.

A bicyclist found Payton after she crawled from the woods to a sidewalk. Payton’s doctor told Muir she nearly died because one wound was so close to her heart. Payton later told her mother that she knew she had to get out of the woods if she wanted to live. Leutner cried as she described listening to nurses count her daughter’s wounds.

"I hugged her, and I said, ‘You’re going to be OK, it’s going to be fine.’ But I could see that she was covered — her arms, and her legs and her abdomen were covered in stab wounds," Leutner recalled.

The alleged attackers have been charged as adults with attempted first-degree intentional homicide. They were found about five hours after the attack walking along a road toward a national forest, where they believed Slender Man lived in a mansion.

Payton’s former best friend is receiving mental health treatment after telling a court-appointed psychologist that she can see and hear things that others cannot — including unicorns, Slender Man and Voldemort, an antagonist in the Harry Potter series. A hearing on the other girl’s mental state is scheduled for next month.

Leutner said she had known of Payton’s best friend for years and hadn’t seen signs of serious problems. She recalled her disbelief when her daughter named her attacker.

"’There’s no way,’ that’s what’s going through my head. (The child) is 12," she said.

Leutner did not know the other girl. The Associated Press is not naming the girls who are charged because their cases could be moved to juvenile court.

"I think about the other parents all the time. I can’t imagine what they are going through," Leutner said.