The two engaged in a foot chase after Smith fled from a traffic stop on August 13. After Smith fell and lay on the ground, Heaggan-Brown approached him and fired again, hitting Smith in the chest from several feet away. The videos show that Heaggan-Brown fired two shots. An official from Milwaukee County's medical examiner's office said that the second shot traveled through Mr. Smith's heart and lung and was "not survivable".
The fatal shooting sparked violent riots in Milwaukee as protesters looted businesses and attacked journalists.
Heaggan-Brown was sacked in October when he was charged with two counts of assault in a separate investigation. "And our argument is that justification did not change over the course of 1.69 seconds between shots", defense attorney Jonathan Smith told the jury.
Heaggan-Brown faces up to 60 years in prison if convicted. He was sacked after being accused of the sexual assault of another man.
"He knew that Sylville Smith was attempting to surrender".
The jury could have found Heaggan-Brown guilty of two lesser charges of second-degree reckless homicide or homicide by negligent use of a firearm.
"According to the complaint, Smith had tossed his gun over a fence and was lying on the ground unarmed when the second bullet killed him", the member station added. Smith, who was armed with a handgun, took off running toward a chain-link fence. Smith and Heaggan-Brown are both black.
The defense team also "argued that Heaggan-Brown was following officer training in ending a threat, and that the former officer could not know whether Smith had another weapon", WUWM added.
"Obviously, everyone recognizes there was a loss of life, and I don't think any officer would want to be put in that situation and to have to make those decisions that he did, but those decisions were made, and I think the jury properly evaluated them", Smith said.
Data shows 82 officers nationwide have been charged with murder or manslaughter for on-duty fatal shootings since 2005, said Philip Stinson, a criminologist at Ohio's Bowling Green State University.
Jury deliberations are entering a second day in the trial of a former Milwaukee police officer charged in a fatal shooting that led to riots in the majority African-American neighborhood where it happened.
Smith's shooting was among a string of killings of blacks by police in recent years that have increased debate about race and policing.