Two 16-year-old high school students have been charged with first-degree murder in the death of a Spanish teacher at their Iowa school, court documents show.

The remains of Nohema Graber, who was a Spanish teacher at Fairfield High School, were discovered in Chautauqua Park in Fairfield, Iowa, on the same day she was reported missing, according to a statement posted on the city's Facebook page.

Willard Noble Chaiden Miller and Jeremy Everett Goodale, both 16, have been criminally charged as adults based on the circumstances and their ages, the city said in the statement.

Each is charged with first-degree murder and conspiracy to commit a forcible felony, according to court records, which also show they are held on a $1 million bond. It is currently unclear whether Miller or Goodale have attorneys.

Preliminary investigation at the scene indicated that Graber -- whose remains were concealed under a tarp, wheelbarrow and railroad ties -- had suffered inflicted trauma to the head, according to a criminal complaint.

In an interview, "an associate" of Goodale and Miller provided authorities with exchanges in social media that indicated Goodale had "specific details of the disappearance and subsequent death of Graber," the criminal complaint stated. The social media interactions also showed that Miller was "involved and present for the death of Graber," according to the complaint.

"The details included, but were not limited to, the motive for killing Graber, the planning and execution of the means to kill Graber, as well as deliberate attempts to conceal the crime," authorities wrote in the complaint.

Miller admitted in an interview to being in Chautauqua City Park "as the murder was taking place, providing materials utilized in committing the murder and aiding in actions taken to conceal the murder," according to the complaint.

"Fairfield Community School District is saddened by the tragic death of longtime teacher, Mrs. Nohema Graber," District Superintendent Dr. Laurie Noll said in a statement. "In her nine years with Fairfield High School, Mrs. Graber touched the lives of many students, parents, and staff."

Miller and Goodale are slated to appear in court for a preliminary hearing on November 12, court records show.

(CNN: Excludes headline)

Update news