Andrea Balcer, who originally went by Andrew, killed her mother and father because she did not believe they would approve of her transition to female.
Balcer's defense attorney said that since his client confessed to killing her parents, Balcer saw no reason to take this to trial.
Prosecutors said that after the murders, Balcer called 911 and told a police dispatcher that she just snapped.
Prosecutors say Balcer later confessed she had been planning to kill her parents all along.
During Thursday's court hearing, prosecutors detailed each and every stab wound tp Alice and Tony Balcer.
The murders took place in the early morning hours of Halloween 2016.
As for the motive, defense attorney Walt McKee said Balcer thought her parents would not be supportive of her transition to Andrea Balcer.
Balcer also pleaded guilty to killing the family dog so it wouldn't bark while she killed her parents.
Balcer also claimed that her mother had sexually abused her but prosecutors said they "do not accept that as reality."
And Balcer's older brother, who was in the basement and was spared that morning, said their parents were loving and supportive.
Prosecutors will ask for the maximum 55-year sentence for a juvenile who is guilty of murder. The minimum sentence is 25 years and the defense will be asking for less.