The murder of an unarmed black man by a white South Carolina police officer would have been ruled justified if not for an eyewitness the size of an index card.

Walter Scott, 50, was running away when North Charleston Patrolman Michael Thomas Slager fired eight shots at his back, five of which hit Mr. Scott. In a traffic stop, Officer Slager pulled his victim over for a broken brake light. Mr. Scott also apparently had a warrant for failing to pay child support. Family said he was terrified of being arrested.

Mr. Scott ran. Officer Scott fired, and Mr. Scott fell. We know this for sure because a bystander captured the tragedy with a cellphone camera. Read the full story and see the video here.

It appears Officer Slager and other officers arriving after the murder didn’t notice the bystander shooting the video, in which Officer Slager is seen walking to the spot where the encounter began, returning to his victim’s body and dropping what looks like a stun gun. Another officer — who appears to be black — watches him do it.

If Officer Slager had known there was video evidence of his crime, he may not have claimed that he shot Mr. Scott in self-defense, fearing for his life after Mr. Scott wrestled away his stun gun. That was the official story and well on the way to being accepted as exculpatory fact until the video turned up.

The footage puts the lie to Officer Slager’s story and appears to show him planting evidence. He has been charged with murder, and the video should be enough for any jury to convict.

Without the video, Walter Scott’s murder would have been recorded as an unfortunate but justified shooting of a ‘thug’ who grabbed a police officer’s stun gun and gave the cop no choice but to cut him down.

Without the video, Walter Scott’s murderer would still be wearing a badge and gun. After being cleared to return to dutyOfficer Slager  would be back patrolling the streets as one of North Charleston’s Finest.