Rachel allegedly became so guilt-ridden that she confessed the entire series of events to her mom, who took her to the Whiteside County Sheriff's Department for questioning.
Anna was charged Tuesday with two counts of first-degree murder, concealment of homicidal death and arson. Though authorities reportedly said Schroeder was shot in the head, her cause of death has not yet been confirmed.
The Associated Press is not naming the girls because they are juveniles. Prosecutors have yet to decide whether they plan to try her as an adult. If convicted, she could be jailed until she is 21.
"My client is a young child and needs to be viewed as the law views her, as a young child", Mertes said. That's when police made their move and arrested the two girls. According to Detective David Molina, she tricked her mom to cover her face with a towel before shooting. Rachel set fire to the bed sheet covering Peggy and to sheets in Anna's room, then they walked to Grove Hill Cemetery, and hid Anna's phone and the gun.
Helm then went to Schroeder's home to help her clean up the bloody mess.
The next day, they are reported to have Peggy's body from the living room to the bedroom and covered her with a sheet before going out to buy more cleaning supplies. She is accused of fatally shooting her mother in the head and burning down their house with a friend to cover up the crime. That same report refers to Anna's alleged accomplice as her "girlfriend".
A separate report from the Sauk Valley News suggests that both teens were planning to run away on Friday night, and had dyed their hair in an attempt to disguise themselves. Ultimately, however, they made a decision to burn down the house in an attempt to destroy the evidence.More news: Two Ukrainian tourists killed in knife attack in Hurghada
Firefighters were called to the home shortly after 1 p.m. Saturday.
Anna is said to have texted her friend Rachel Helm, also 15, to confess that she had killed her mother on Thursday, Sauk Valley News reported.
Police said Anna also texted Rachel a photo of her mother's body when she refused to believe she had shot her. "She was the kindest person", Kaylene Schroeder, 18, told WQAD of her mother, Peggy.
A 15-year-old is being charged with first-degree murder in the gruesome death of her mother. If you can, I just want you to know you were my best friend. There were so many things I wanted to say and do with you. But I wasn't the best daughter.
She says she will always remember how much her mom loved to garden and was always helpful to everyone, but says now she's just trying to pick up the pieces.
The message was followed by two heart icons.
Schroeder's sister also took to Facebook to grieve, according to SaukValley.com, where she wrote, "It warms my heart to see all the love and attractive words from all of [Peggy's] friends".