A white Virginia police officer was convicted of voluntary manslaughter Thursday in the fatal shooting of an unarmed black 18-year-old accused of shoplifting.

A circuit court jury found former Portsmouth police officer Stephen Rankin guilty for the killing of William Chapman in April of last year. It was the second time Rankin had killed an unarmed man while on duty. He now faces up to 10 years in prison, although the jury recommended just 2 1/2 years.

Earlier on Thursday, lawyers for Rankin had unsuccessfully urged the judge to declare a mistrial, citing video evidence showing a friend of Chapman’s family speaking to a juror. Rankin’s defense described this as a deliberate attempt to influence the outcome of the trial ― a charge that the friend denied.

Rankin, who was fired while he awaited trial, had originally been charged with first-degree murder and using a firearm to commit a felony.

On the morning of April 22, 2015, Rankin approached and tried to stop Chapman in the parking lot of a local Walmart to investigate a security guard’s accusations that the teen had shoplifted from the store. There is no video of the encounter between Chapman and Rankin, and some of the details remain disputed.

Most witnesses who testified in the trial said Chapman had his hands up when Rankin approached him. Shortly thereafter, Rankin said, the teen knocked the officer’s stun gun to the ground and charged toward him. Some witnesses backed Rankin’s account, saying Chapman did charge. One witness said the teen took a swift step toward the officer, as if to make him flinch. Rankin said that he did not want to hurt or kill Chapman, but that he had no other choice than to open fire.

It still remains unclear if Chapman actually did shoplift from the store that morning, The Guardian reported.

After fatally shooting the teen in the face and chest, Rankin allegedly told a witness, “This is my second one.” The officer had been involved in another fatal on-duty encounter four years earlier, when he killed Kirill Denyakin, an unarmed 26-year-old cook from Kazakhstan, in a hail of 11 bullets. Rankin later admitted to using a pseudonym to defend the shooting in an online forum. While a grand jury declined to indict him in Denyakin’s death, his superiors barred him from patrol duty for three years.

It’s exceedingly difficult to convict a police officer in the rare instances in which one is prosecuted. Across the country, only 74 officers have been charged with murder or manslaughter stemming from an on-duty shooting since 2005, according to data from Philip Stinson, an associate professor of criminology at Ohio’s Bowling Green State University. Rankin may be only the 26th police officer to be convicted of such a charge in that timeframe.

Stinson’s data don’t include cases in which civilians died in police custody or were killed by other means, or those in which officers faced only lesser charges.

The small number of convictions in fatal police shootings looks even smaller when you consider how many such shootings occur each year. Although there are no reliable government statistics on civilians killed by police, data compiled independently by media outlets like The Guardian and The Washington Post and by civilian tracker Mapping Police Violence have led to estimates of roughly 1,000 deadly shootings each year.

The overwhelming majority of police shooting cases are ultimately determined to be justified homicides, in which deadly force was used lawfully, often in what police say was an effort to protect an officer’s safety or to prevent harm to the public.

One reason for the lack of prosecution and subsequent conviction even in questionable police-involved deaths is the Supreme Court’s legal standard for use of lethal force. Under Graham v. Connor, the 1989 case that set forth the standard, each “use of force must be judged from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight.” The ruling specifically cautions against judging police too harshly for split-second decisions made in “tense, uncertain and rapidly evolving” situations.

Another reason that officers walk free is that judges and juries tend to side with the police.

All things considered, Stinson said a murder conviction for Rankin was unlikely. “The Rankin verdict makes sense to me ― as soon as I heard testimony during the trial from another officer that when he arrived on the scene right after the shooting, Rankin was performing CPR on the man he had just shot,” Stinson said. “There’s no way a jury would convict a police officer on a murder charge with those facts.”

Law enforcement agencies have also traditionally controlled the public narrative of these events ― that is, until recently with the rise of mobile phone videos and the use of police body cameras.

While Stinson doesn’t expect to see more officers charged in coming years, he said video of these shooting incidents has the potential to drive reform.

“What we see over and over in the videos is that the videos contradict the narratives given immediately after shooting by police on the scene and that officers involved in these unjustified shootings are not acting in ways consistent with their training,” he said.