Slager, 33, was charged Tuesday with first-degree murder after firing eight shots at Scott, killing him.
Slager is also now "terminated" from the force, North Charleston Mayor Keith Summey said Wednesday.
Added police Chief Eddie Driggers on Wednesday: "I watched the video, and I was sickened by what I saw and I have not watched it since."
Both Scott and Slager had once served in the U.S. Coast Guard, with Scott's service occurring 1984-86 and Slager's 2003-09. Scott was a father of four. Slager is a father to two stepchildren, and his wife is eight months' pregnant.
Here's what we know of the fatal shooting:
9:33 a.m.: Vehicle violation
Slager pulled Scott over at 9:33 a.m. Saturday for a broken taillight, according to authorities.
Chief Driggers described the incident as "traffic stop of an individual who had a minor infraction on his vehicle, a brake light being out."
A foot chase then occurred, a police report said.
The video, taken by a passer-by, doesn't show any vehicle.
Rather, Slager and Scott are on a path or roadway in a parklike setting bordered partly by a chain-link fence. The video was shot over and through the fence.
"The officer said that Walter ran from the vehicle during the traffic stop," Scott family attorney L. Chris Stewart said.
According to the police report, Scott did not comply with the officer's demands.
Scott's brother, Anthony Scott, said his brother had trouble with child support and had an outstanding warrant against him, but that his sibling wasn't prone to violence.
"That very well could have been the reason (for running from police), not to be arrested for the warrant that was on him for child support," Anthony Scott said.
The video begins by showing a second or two of an apparent struggle between the officer and suspect.
The officer contended he used a Taser stun gun on Scott and that Scott tried to take that weapon, authorities said.
But when Anthony Scott saw the video, he was convinced the officer lied, he told CNN.
"There was not a struggle for the Taser," Anthony Scott said. "I didn't believe my brother would have done that anyway."
The video shows Walter Scott running away, with his back to the officer.
As he does so, two objects fall. One falls behind the officer. And the other falls between the two men.
To Anthony Scott, the videotape shows his brother was "running for his life" away from the officer to escape more of the Taser.
"I think my brother was thinking he was not going to be shot. No one would have thought that," Scott said.
As Walter Scott runs away, the officer pulls his service pistol and fires eight times, the video shows.
As the shots are being fired, Scott keeps running away from the officer, the video shows.
Scott then falls.
Later in the video, when the officer approaches Scott's body, he drops a dark object next to the man. It's not clear whether it is the Taser.
It's also unknown whether Scott took the officer's Taser, or whether the officer picked the object up and moved it closer to the body.
Immediately after Scott was shot, according to the video, someone yells, "Put your hands behind your back!"
Scott, motionless and face-down on the ground, is handcuffed.
9:38 a.m.: 'Subject is down'
It was Slager who apparently called police dispatch.
"226 to dispatch, shots fired, subject is down. He grabbed my Taser," Slager told the dispatcher, according to a transcript provide by Broadcastify.com.
The dispatcher notes that the subject is down at 9:38 a.m., according to the transcript.
9:40 a.m.: Description of wounds
About 90 seconds after saying that Scott "grabbed" his Taser, the officer describes Scott as unresponsive and having wounds to the chest, right thigh and buttocks, according to the transcript.
The location of the shooting is behind a pawn shop, the officer tells the dispatcher. A police report identified that shop as Mega Pawn.
According to CNN affiliate WCIV-TV
in Charleston, Slager initially said through his attorney, David Aylor, that he followed the appropriate policies and procedures.
However, Aylor later told CNN that he was no longer representing the officer.
"Today, I withdrew my representation of Michael Slager. This is a terrible tragedy that has impacted our community," Aylor said in a statement.
Saturday: Learning of a brother's death
Later, Anthony Scott's mother calls him and says his brother was Tasered at a traffic stop.
Anthony Scott goes to the scene and finds it curious to see police tape around his brother's vehicle and the officer's vehicle.
He asks officers what happened. No one replies.
Then Anthony Scott's nephew tells him that "my brother is gone," Anthony Scott said.
"And at that, I lost it," Anthony Scott said.
An officer also apprises him later of what happened.
Sunday: First viewing of video
Anthony Scott is shown the video for the first time on Sunday.
"My reaction to it was that we have to get ahold of the video and that this was key evidence, key evidence in the case," Anthony Scott said. "We had to get it. The country had to see this."
He felt "a little bit of anger and happy at the same time," the brother said.
"Based on what the video was showing, it was discrediting what the officer had initially stated," Anthony Scott said.
The nation did indeed see the video -- and was stunned by its revelations.
Authorities saw it, too.
Tuesday night bond hearing
Slager was denied bail at a bond hearing Tuesday night, WCIV reported.
"I have two stepchildren and one on the way," Slager told a magistrate through video conferencing.
If found guilty of murder, Slager could face up to life in prison or death.
The city of North Charleston will continue to cover the insurance for the pregnancy of Slager's wife, the mayor said.
An autopsy on Scott, performed Sunday, "revealed that Mr. Scott sustained multiple gunshot wounds to the back of his body and the manner of death was ruled 'Homicide,' " Charleston County Coroner Rae H. Wooten said Wednesday.
Anthony Scott said Wednesday that his brother was "shot in the back four times."
The autopsy findings support family's claims that the police used excessive use -- even if the video never existed, Anthony Scott said.
"Eventually we would have gotten to this point, but not this fast," Anthony Scott said.
"There is absolutely no way to cover that up," he added about the gunshot wounds to the back.
North Charleston police aren't involved in the investigation into the shooting and have turned the matter over to the South Carolina Law Enforcement Division.
The FBI is also investigating.
Family's interpretation of video
Anthony Scott and family attorney Stewart believe the object that Officer Slager relocated at the crime scene is the Taser, they said.
Stewart also accused the officer of trying to plant evidence by moving the Taser and placing it close to Walter Scott's body.
A slow-motion analysis of the tape, along with highlights of key moments, supports the family's step-by-step interpretation of the officer's actions, including the handling of the Taser, the attorney alleged.
"He drops the Taser, kills Mr. Scott, walks all the way back, picks something up off the ground from where he was taking the shots, comes back to the body, waits a second, drops it on the ground, and then pretends to be recovering it and putting it back on his holster," Stewart said, referring to the Taser.
"Why we believe that is because it fits in line with his initial report of what happened out there. I mean he just committed a murder. He needed something, a justifiable reason to use lethal force, and that's the only thing he could think of," Stewart said.
Neither Officer Slager or his attorney could be reached for comment Wednesday.
Authorities aren't commenting on the details of the case while it's under investigation.