Iowa teens killed their Spanish teacher over "poor grade," prosecutor says

Two Iowa teenagers killed their high school Spanish teacher last year because of frustration over a bad grade, prosecutors said Tuesday in court documents that for the first time reveal a possible motive.

The documents were filed ahead of a hearing Wednesday where a judge will hear arguments on whether to suppress any of the evidence against Willard Miller and Jeremy Goodale, who are charged with murdering high school Spanish teacher Nohema Graber in the small town of Fairfield.

A lawyer for Miller is asking the court in Fairfield to invalidate four search warrants and suppress evidence from Miller's home, comments he made to police and information taken from his cellphone and the social media platform Snapchat.