South Carolina police officer Michael Slager has been charged with murder after video emerged of him shooting a black man running away from him.

State investigators arrested North Charleston Officer Michael Slager on April 7 after viewing the mobile phone video of the shooting.

According to authorities, victim Walter Lamer Scott was shot after the white officer had already targeted him with a stun gun.

The US Department of Justice is set to launch an investigation.

“When you’re wrong, you’re wrong,” North Charleston Mayor Keith Summey said, announcing the arrest.

“When you make a bad decision, I don’t care if you’re behind the shield or a citizen on the street, you have to live with that decision.”

Photo North Charleston Police

Police officers in the US fatally shoot and kill hundreds of people each year, but only a handful of cases result in the officer facing criminal charges.

The incident on April 4 began after Walter Lamer Scott’s car was stopped for having a broken rear light, local media reported.

A video of the incident published by the New York Times shows a brief scuffle before Walter Lamer Scott begins running away. The video then shows Officer Michael Slager firing several shots at Walter Lamer Scott, who falls to the ground.

The Post and Courier newspaper of Charleston reported that Walter Lamer Scott had been arrested about 10 times, mostly for failing to pay child support or show up for court hearings.

His brother, Anthony Scott, told the Post and Courier that he believed his brother fled from Michael Slager because he owed child support.

Anthony Scott said that because of the video, “we have received the truth” and “through the process, justice has been served”.

Chris Stewart, a lawyer for Walter Lamer Scott’s family, called the passer-by who recorded the video a “hero”.

The shooting occurred as heightened scrutiny is being placed on police officer shootings, particularly those that involve white officers and unarmed black suspects.

A grand jury declined to indict Ferguson, Missouri officer Darren Wilson over the fatal shooting of Michael Brown last August, leading to nationwide protests.

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