The 24-year-old woman is being held in the Lyon County jail on suspicion of second-degree murder, but no formal charges have been filed.
Twenty-six-year-old Ricky Nurnberg was found dead at the couple's apartment Wednesday night. Police say he had been beaten.
Assistant Lyon County Attorney Amy Aranda says prosecutors have not decided when or if to charge the suspect.
Police Chief Gary Smith says there is no evidence that anyone else was involved in the death.
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