The coroner says in a preliminary ruling that the woman drowned.
But Prosecutor Rachel Hutzel said Wednesday that officials found signs of "violent force" and injury to Sarah Widmer's body inconsistent with an accidental drowning.
Ryan Widmer was being held in the county jail. His lawyer Charlie Rittgers says he doesn't understand why investigators believe the death wasn't accidental.
Authorities say the couple had been married about six months.