'Slender Man Stabbing' 12-Year-Old on Attacking Classmate: 'We Were Trying to Kill Her'

This week a judge will determine how long Morgan Geyser, one of the two girls who attempted to stab their classmate to death back in 2014, will be committed to a mental facility.

On May 31, 2014, Geyser and her classmate Anissa Weier lured their classmate Payton Leutner into the woods in Waukesha, Wisconsin, and stabbed her 19 times. The attempted murder would go on to be known as the "Slender Man Stabbing" as the two claimed afterwards they were influenced by the Internet and video game fictional character The Slender Man.

All three girls were 12-years-old at the time of the incident.

ABC News obtained the footage from Geyser's police interrogation where she admits to the stabbing. The footage will be shown on Friday on the next episode of 20/20, which will focus on the attempted murder. A sample of the video was released to PEOPLE, along with a sneak peak of an interview with Geyser's mother, Angie Geyser.

When asked by the police why she and Weier led Leutner into the woods, Geyser did not hesitate to reveal their intentions.

"Kill her," Geyser said. "I might as well just say it, we were trying to kill her."

When reviewing the tape, Angie said her daughter never acted the way she did in that interrogation.

"The interrogation is very difficult to watch because that's not my daughter saying those things. That's not the way that she speaks, that's not the way that she acts," Angie said.

Geyser goes on to ask the interrogator what happened to Leutner, bluntly stating she was the one who stabbed her

"Do you know what happened to Bella," Geyser said. "She's not Anissa, she's the one whom I stabbed. ... Is she dead? I was just wondering."

"(She) appears to have no remorse for what's happened and she just talks about it in such a flat manner," Angie said of her daughter.

Despite her injuries Leutner managed to survive the attack. Geyser was charged with first-degree attempted murder, while Weier was charged with second-degree attempted murder. Both were charged as adults and both pleaded guilty.

The jury determined Weier was mentally ill at the time of the stabbing and was committed to a mental facility for 25 years. As part of Geyser's plea deal, she too was not criminally responsible due to mental illness, which her family said is a diagnosis of early-onset schizophrenia.