Prosecutors in Iowa have alleged that two teenage boys beat their Spanish teacher to death over a bad grade.
Nohema Graber, 66, disappeared on 2 November last year after going for a walk in Fairfield, and her body was found the next day, hidden under a tarp, railroad ties and a wheelbarrow.
Jeremy Goodale and Willard Miller were charged with the murder of their teacher, both aged 16.
New documents filed this week revealed the prosecutors alleged motive for the murder, that it was over a bad grade given to Miller.
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