Washington: A chilling video captured the final moments of Walter Scott`s life. Empty handed, he runs from a police officer who pulls his gun and fires eight shots.
This footage, which follows spate of other cases of officers killing unarmed civilians, has some accusing US police of using excessive force and getting away with it.
After white officer Michael Slager shot at Scott -- striking him five times -- the African American father of four crumples to the ground.
Slager rushes over and handcuffs him as he breathes his last, his face in the grass.
Though there are no national statistics on how many people die at US police hands each year, Human Rights Watch said that out of more than 2,700 police-involved deaths deemed "justifiable" by authorities between 2005-2011, just 41 officers were charged.
According to US law, the use of deadly force by police is justifiable if a suspect poses a credible threat to the officer or the public.
Police can also sometimes use deadly force on a fleeing suspect if they think he has committed a crime and is likely to escape.
However, each state`s law differs, and there are 18,000 disparate law enforcement agencies in the United States.
Slager had argued he felt threatened, but after the video was released Tuesday, the officer was charged with murder and later fired from the force, a rare punishment for an officer.
"This appears to be an out-and-out execution. He just shot this man in the back, shot at him eight times," argued Randolph McLaughlin, law professor at Pace University.
For him, training officers -- including in race relations -- is crucial, since they make split-second decisions in high-stress scenarios.
"If we don`t train officers properly, then innocent people will be killed. And we see a rash across the country of officers shooting," McLaughlin told AFP.
The combination of inadequate training and racial bias, he said, creates a "toxic stew."
Civil rights lawyer Michael Haddad said police are often trained to use their guns more readily than in the past.
"Police officers are trained to shoot sooner rather than later to avoid even the slightest risk to themselves no matter how great of a risk the police pose to the public," said Haddad, who is also the president of the National Police Accountability Project.
"They receive much less training about when it is appropriate and lawful to shoot," he added.
Scott`s death comes in the wake of a string of killings by police, including the shooting of 18-year-old Michael Brown in Ferguson, Missouri, which sparked sometimes violent protests across the country.
And in July, African American father-of-six Eric Garner, 43, died after being held in a police chokehold for several minutes. The incident was also caught on tape, and Garner is heard saying "I can`t breathe" several times. But police say they are wrongly accused of harboring a racial bias and are mostly within legal bounds when they use lethal force.
"In most instances, the force employed by a police officer is reasonable. It`s within policy and that`s why you don`t see any criminal charges against the officer," said Delroy Burton, chairman of the DC police union.
"We`re scrutinized for a lot of things, unfortunately. Whenever something happens and race is injected, reasonableness goes out the door."
A 2013 national crime report from the FBI said there were 461 justifiable deaths by officers, 426 in 2012 and 404 a year earlier.
By comparison, non-profit group Inquest said 26 people in Britain were killed by police last year, compared to 31 in 2013 and 24 the year before that.
"We have a gun culture and that`s part of our problem," said McLaughlin.
He said more police in the United States carry firearms compared to countries with lower police-involved killings, including Canada or Britain.
The police killings have also raised questions about how investigations into officer use of deadly force are conducted.
They are often carried out by local prosecutors, though the Federal Bureau of Investigation will sometimes launch its own probe.
In some cases, as with the officers that killed Brown in Ferguson and Garner in New York, the police were investigated by local prosecutors before appearing before a grand jury. Neither officer was indicted.
McLaughlin said it is rare for an officer to be punished under such an arrangement because prosecutors tend to sympathize with police.
"We`re stuck at the state level... but I think we need more federal intervention," he said.
Despite varied training and investigations across the country, most officers are well-meaning, apart from a few bad apples, said David Klinger criminologist at the University of Missouri-St Louis.
"Most police officers don`t want to get involved in a shooting, but if they do, what they`re not going to want to do is to get involved in a shooting with a black individual," he said.
"They are well aware of this narrative and they`re afraid that they are going to be accused of shooting out of racial animus."
