Matthew Oropeza admitted to punching Drew Justice in the face after Justice told him to keep his dogs on a leash.
Prosecutors say witnesses saw 25-year-old Oropeza letting his two dogs run around when 38-year-old Justice, who was walking his dog with his fiancé, confronted him about the rule.
They say Oropeza was furious and went over to Justice screaming "Say it to my face!" At that point, the defendant punched Justice in the face. Justice fell backwards, hitting his head on the pavement, and later died at the hospital.
After throwing the punch, Oropeza gathered his dogs and took off in his car. He was later identified because of a similar quarrel with another man in the same park. That man took a picture of the Oropeza's license plate.
Oropeza will be sentenced in May. Charges of simple assault and reckless endangerment were dropped, but there is no negotiated plea. He faces the possibility of serving five years in prison.