Everyone who has seen the footage of Tyre Nichols' fatal encounter with five Memphis police officers has come to the same conclusion: something went horribly wrong that night.

Lawyers for his family said the officers acted like a "pack of wolves" and beat him "like a human pinata".

Police Chief Cerelyn Davis, who is the first black woman to serve in the role, told the BBC she was shocked. "Something happened that we can't explain," she said.

The videos prompted the authorities to fire the five officers earlier this week, and then to charge them with offences including second-degree murder.

On Friday evening, the videos were released to the public. The footage did show the harrowing events that led to Mr Nichols' death, but many questions still remain.

Why did police pull him over?

While the four videos contain over an hour of footage total, capturing multiple angles taken from police body cameras and a pole-mounted surveillance camera, one crucial element is missing: how did all this begin?

His family has said that Mr Nichols, an avid photographer, was out driving so he could take pictures of the sunset.

Officers initially said Mr Nichols was pulled over for alleged reckless driving, but police on Friday said there is no evidence to substantiate that claim.

The footage released only begins after police confront him at an intersection at 8:24pm local time - police say the initial traffic stop was not filmed but we don't know why.

Tyre Nichols

He is immediately dragged out of the car and thrown to the ground by officers with guns drawn.

"I didn't do anything!" Mr Nichols says early on, and he complies with the officers' instructions.

An officer shouts: "Put your hands behind your back before I break your [expletive]."

"You guys are really doing a lot right now," Mr Nichols says to the officers. "I'm just trying to go home."

Later in the video, we hear an officer telling other officers who have arrived at the scene that Mr Nichols swerved and almost hit his police vehicle, but we see no evidence of this.

Another officer claims he thinks Mr Nichols may be "on something," which implies they believed he may have been using drugs. There is no known evidence that this was the case, and later in the video, officers say they did not find anything in his car.

Why were the officers so aggressive?

From the get-go, the officers are very hostile, cursing at Mr Nichols and telling him to lie on the ground or they will tease him.

In the videos, Mr Nichols is initially compliant, if confused, by the officers' hostility. He lies down on the ground as instructed, as they attempt to handcuff him.

But when one of them tries to tease him, he breaks free and tries to run, at which point police pepper spray him.

How he broke free, and why police were so aggressive in the first place, is not clear.

"It was incomprehensible, from beginning to end," Greg Donaldson, a professor at the John Jay College of Criminal Justice in New York, told the BBC.

"From the car stop, the state of agitation of the police when they pulled the car over, to the pursuit, to the lack of training and lack of strategy in containing and subduing the person they had stopped."

Why did they continue to assault him?

Mr Donaldson says the video seems to show that police anger grows "as their incompetence seems to be more revealed".

Spraying his eyes with water after feeling the effects of the pepper spray himself, one of the officers says they should "stomp" him when they catch him.

That is exactly what they do in the videos that captured the second encounter which began at 8:32pm. For several minutes, police punched and kicked him, in the body and the head, while Mr Nichols cried for his mother. One officer is seen wandering away, breathing heavily. Almost a minute later, he returns to the scene, pulls out his extendable baton and strikes Mr Nichols repeatedly.

None of the officers try to stop him, or another who is seen punching Mr Nichols in the head at least five times.

"This incident just ran out of control," Mr Donaldson says.

Why did no one help him?

It is evident from the footage that Mr Nichols is in distress after the beating. He writhes on the ground before being slumped up against a car, unable to properly sit up himself.

Still from footage of Tyre Nichols brutal encounter with police

"The worst part of it was the lack of humanity after the incident," Mr Donaldson says.

The officers "stood around like its as just an afternoon on the street," he says, while leaving Mr Nichols "laying there on the ground like a piece of garbage".

There are more officers on the scene than bodycams released, and we do not know if there is additional footage.

Medics arrive to examine Mr Nichols at 8:41pm. Twenty minutes later a stretcher comes into view in the video and then an ambulance arrives. We don't know how long it is before Mr Nichols is taken to hospital.

What is the cause of his death?

Although it is clear Mr Nichols was severely beaten, we still do not know what actually caused his death in hospital three days later.

In the video, we do see police kick him in the head twice, and there is blood visible around his face.

Attorneys for his family have said that an independent autopsy found that he suffered "extensive bleeding caused by a severe beating," but the full report has not been made public. (BBC)

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