An Iowa teenager who killed his Spanish teacher was sentenced to life in prison Thursday, court documents show.

Willard Noble Chaiden Miller and Jeremy Goodale were both 16 when they killed Nohema Graber in 2021.

They both pleaded guilty to first-degree murder.

Miller was sentenced after a seven-hour hearing, according to Jefferson County Attorney Chauncey Moulding.

"I feel that the sentence was fair and appropriate under the gruesome and horrific circumstances of this case, and feel that justice was done," Moulding told CNN in an email. "I believe this sentiment is generally shared by the Graber family and the community of Fairfield."

Miller will be eligible for parole after 35 years, court documents say.

Goodale's sentencing is scheduled for August, CNN affiliate KCCI reported. His lawyers asked for a delay for a psychiatric evaluation.

Graber taught at Fairfield High School. Her remains were discovered in Chautauqua Park in Fairfield, Iowa, on the same day she was reported missing, authorities said at the time.

Her remains were concealed under a tarp, wheelbarrow and railroad ties, they said. She had suffered inflicted trauma to the head, according to a criminal complaint.

CNN has reached out to Miller's attorney Christine Branstad for comment.