FAIRFIELD, Iowa (WHO) — Prosecutors for the State of Iowa have revealed a possible motive for the murder of a Fairfield High School teacher one year ago in new court filings.

Willard Miller and Jeremy Goodale are each charged with first-degree murder for the beating death of Nohema Graber on November 2, 2021. Goodale is scheduled to go on trial next month. Miller’s trial is set for March 2023.

Christine Branstad, the attorney representing Miller, is seeking to have a search warrant used in the investigation and the evidence it uncovered be disallowed at trial. A judge will consider the motion in a hearing on Tuesday. In paperwork filed ahead of the hearing, the state will contend that it had every right to request a search warrant.

In those documents released Monday, the state lays out the evidence that led them to request the search warrant. Most damning among that evidence are images of Snapchat messages sent from Miller to friends wherein he admits to the murder, prosecutors say.

Prosecutors also laid out the witness reports and evidence they followed that put Miller, Goodale and Graber in the same place at the time of her murder. According to the documents, Nohema Graber was known to walk in a local park every day after school. Her van was seen leaving Chautauqua Park around 4:42 p.m. Witnesses later reported seeing two males in the front seats of the van. A short time later two males were seen walking away from Middle Glasgow Road. Graber’s van was later found on Middle Glasgow Road, a half-mile from where the two males were seen walking. Goodale later called a friend and asked him to pick them up on Middle Glasgow Road that evening.

Prosecutors also point to a potential motive for Graber’s murder. Miller had a meeting with Graber on November 2nd, 2021 – the day she was killed – to discuss his poor grades in her Spanish class. Authorities believe Miller killed Graber in retaliation for his poor grades.

Authorities say Miller at first denied any knowledge of Graber’s murder, then said he knew about it but didn’t help. He later said that he was forced by the “real killers” to use his wheelbarrow to move her body. He also claimed a group of masked kids made him assist them.