LINCOLN, Neb. -- New details are emerging in a Lincoln shooting.

Lincoln Police say 80-year-old John Kotopka shot his wife in the head over the weekend. He now says it was because of her Alzheimer's.

Kotopka tells police 78-year-old Janet Kotopka had been diagnosed with Alzheimer's two years ago. He claims she became "combative" and agressive. This, he says, led him to become exhausted and start to consider killing her 10 days prior.

According to Lincoln Police Department, Janet Kotopka died from her injuries early Wednesday morning. Prior to her death, Kotopka was charged with first degree assault and use of a deadly weapon. Police say the charges could be re-evaluated and an autopsy will be scheduled. 

His next court date for first-degree assault charges was scheduled for July 20th. Officials have not said whether or not that date will change pending Wednesday's developments.