Video footage shows Slager pursuing and fatally wounding Scott even though his life was not in danger, prosecutors said.
During his testimony, Slager argued that he caught up with Scott and they scuffled before the shooting. He claimed Scott was stronger than him and wrestled away his Taser, briefly pointing it at him before running.
Slager said that even at 18 feet away, Scott posed a threat to him. Prosecutors contended there was little physical evidence of a struggle.
There are no degrees to a murder charge in South Carolina. If convicted, Slager faces 30 years to life in prison.