As part of his plea agreement, Tyler Wicklund, 24, also pleaded guilty to aggravated robbery and felony possession of a firearm, while four other felony counts were dismissed. Wicklund was originally charged with second-degree murder, but a grand jury came back with a first-degree murder charge.
An Oct. 10 trial date was erased when the guilty plea agreement was entered.
First-degree murder carries a maximum sentence of life in prison.
Wicklund was accused of killing his ex-girlfriend, Jessica Buboltz, last October after confronting her about a new boyfriend.