Here’s everything we know about the November killing of 66-year-old Nohema Graber.
The suspects and charges
Authorities in southeast Iowa have formally accused Jeremy Goodale, 16, and Willard Miller, also 16, of first-degree murder and conspiracy to commit murder in the death of Ms Graber.
Both suspects attended Ms Graber’s Spanish class at Fairfield High School, but no disagreement or animosity between them have been established.
The timeline of events
Details about Ms Graber’s last moments were included in a court filing on 23 December – alleging that both students watched her closely before she was ambushed in an attack on 2 November.
They reportedly monitored her daily walk, during which prosecutors say Mr Goodale and Mr Miller ambushed their Spanish teacher and dragged her body into a nearby forest. They returned later to better hide the body.
The Fairfield High School teacher was reported missing on the morning of 3 November and she was found hours later in a park in the area, about 95 miles (150 kilometres) southeast of Des Moines.
Her body was covered by a tarp, a wheelbarrow, and railroad ties. Her body had signs of “inflicted trauma to the head”, authorities have said.
Mr Miller also told investigators he was at the park on 2 November and he provided some of the tools allegedly used in the killing.
Police were able to arrest Mr Goodale and later Mr Miller after receiving a tip-off about both students discussing the attack on social media, court documents said.
There were also clothing items, which appeared to be stained with blood, left behind at the park in Fairfield that connected the death to both students, who appeared in court for a hearing on 23 December.
Judge Joel Yates said he reviewed the information and the minutes of testimony and found “they contain evidence which, if unexplained, is sufficient to warrant a conviction by a trial jury”.
Ms Graber had been teaching Spanish at Fairfield High School since 2012. Police have said that Ms Graber often visited the park where her remains were discovered.
“My heart goes out to the family, friends, colleagues, and students that are dealing with this tragic murder of Nohema Graber,” Governor Kim Reynolds said. “Ms Graber touched countless children’s lives through her work as an educator across our state by sharing her passion of foreign language.”
“I am confident through the work of our dedicated law enforcement that justice will prevail,” she added.
What happens next?
Both individuals are being held on a $1m cash bond in juvenile detention facilities, and both have pleaded not guilty. A hearing has been scheduled for 27 January and the teenagers are set to stand trial in April, KYOU-TV reported.
The teenagers will be tried as adults because if found guilty as juveniles, they could be released within two years at 18-years-old, Jefferson County Attorney Chauncey Moulding argued. Lawyers for both of the teenagers have asked that they be tried in juvenile court.
“This prosecuting attorney cannot fathom any combination of programming at any Iowa juvenile facility which could appropriately treat or rehabilitate the defendant if adjudicated as a juvenile,” Mr Moulding said.
If convicted for first degree murdrer as an adult, the sentence in Iowa would be life in prison, but a 2016 decision from the state Supreme Court requires that juveniles be afforded a chance to be released after being given a life sentence.
The Associated Press contributed to this report