Twenty-four years ago, I watched a police officer shoot a man. It was right outside a supermarket, the Acme Market on Route 40 in Havre de Grace, Maryland. A ferocious thunderstorm had rolled through, all noise and eerie green light, while we were shopping, and the parking lot was still flooded with rain.

Word had filtered in from the rest of the shopping plaza that a man was out there with a knife, waving it at people, menacing them. And there he was—an old man, with glasses and a Santa Claus beard—just a little ways down, to the left. I couldn’t see the knife myself.

Someone had called the police, and a squad car came speeding up through the sheeted water and an officer got out. Maybe there were other officers around, in the background. It was all confusing but in certain respects it was very clear. The officer had his gun out. He shouted Drop it at the man. From where I was, I still couldn’t see the knife.

The old man didn’t drop anything. He walked toward the police officer. The officer told him, loudly, to drop it, over and over. The officer backed up, gradually, from the open front door of the car to somewhere near the back of the car, gun up, in a firing stance. Drop it.

The man did not drop anything, and he kept walking. The logic of what was going on was simple and awful. The officer had told him to drop it and he hadn’t dropped it. The officer had given him space and he was advancing through the space. What had to happen next was obvious.

The officer fired.

The pistol sounded remarkably small out there in the open. The man stopped, and at last I saw the knife, a long pale triangle dropping from his hand and splashing on the flooded pavement. The officer held his stance. The man fell down.

Somewhere behind me a woman wondered aloud if the cop was using blanks. The question was funny, almost. It was unbelievable, what she’d just seen. An ambulance came right away. I would read later in the local newspaper that the man was treated for a single gunshot wound to the leg. It seemed like he was OK, except for whatever had made him wander around brandishing a knife in the first place.

A few days later I went to the movie theater and saw Thelma & Louise, and it wasn’t enjoyable to watch just then. That was my own feeling, not really a generalizable one about the movie. I had just watched a man get purposely shot, and I didn’t like watching people get shot or watching people play around with guns.

Now, 24 years later, on video, I could see the Chicago police shoot Laquan McDonald for carrying a knife. The initial official account of the shooting, attributed to Pat Camden, a spokesperson for the Chicago Fraternal Order of Police, described a series of events remarkably close to the events I saw in person on that parking lot:

The teen began walking toward Pulaski Road and ignored the officers’ requests to drop the knife, Camden said....

Officers got out of their car and began approaching McDonald, again telling him to drop the knife, Camden said. The boy allegedly lunged at police, and one of the officers opened fire.

McDonald was shot in the chest and taken to Mount Sinai Hospital, where he was pronounced dead at 10:42 p.m....

“When police tell you to drop a weapon, all you have to do is drop it,” Camden said.

This story that Chicago’s Fraternal Order of Police told is a very reasonable story. It has, more or less, the logic of the incident I witnessed—being “shot in the chest” is more drastic than being shot in the leg, surely, but lunging with a knife is more drastic than what the old man was doing.

The reasonableness of this official account makes it all the more appalling when you watch the video and see that it is a lie. The officer who shoots Laquan McDonald—reportedly Jason Van Dyke, who has now been charged with first-degree murder—does not approach him, and is not lunged at. The officer jumps out and opens fire from the side, yards away from knife range, and he keeps pumping bullets into McDonald long after McDonald is down on the ground. McDonald was not “shot in the chest,” or rather, by the Cook County medical examiner’s diagrams, he was shot in the chest, but also the back, shoulder, leg, head, neck, and arms. He was slaughtered.

The difference between the Chicago video and the shooting I witnessed is terrifying and, by now, familiar. I have seen the difference over and over again lately: in the video of Officer Michael Slager of North Charleston, South Carolina, pouring five rounds into Walter Scott from behind as Scott fled a traffic stop. In the video of Officer Sean Williams of Beavercreek, Ohio, opening fire on John Crawford III as Crawford talked on the phone while holding a BB gun in a Walmart aisle.

And in the video, recorded a year ago last week, of Cleveland police officer Timothy Loehmann leaping from his squad car as it comes to a halt and gunning down 12-year-old Tamir Rice. It takes less than two seconds.

The videos are horrible. One line of criticism holds that they are too horrible, that distributing and watching them is itself an act of violence and exploitation. Yet in case after case, they are the only thing that breaks through the lies.

The lie, again and again, is that the police had no choice. On that street in Chicago, in that Walmart, on that Cleveland playground—over and over, rather than creating the time and space to assess a potentially dangerous situation, the police were the ones making sure it was dangerous. They eliminated all other possibilities, rushing in to deliver lethal force as fast as they could. The police in these videos are clearly trained and prepared to kill first and to justify the killing later.

The murder charges in Chicago merely emphasize how vast the gap is between principle and practice. The slaying of Laquan McDonald was flagrant and inexcusable. And it was done in front of at least four other police officers, who let it happen and tried to let it go unpunished.

These killings are the opposite of what I watched the police officer do in 1991. That officer made sure to do nothing that he didn’t have to do. He was there to protect life, including even the life of an armed and apparently dangerous suspect.

This is the principle that the Chicago and Cleveland police recognize by lying about it. The police are supposed to be putting their own lives at risk, for the sake of civilians. They know this is what their claim to honor rests on. They just don’t practice it.

Instead, the police on video act as combatants, with the public as the enemy. They strike with overwhelming force and, in the cases of Tamir Rice and of Walter Scott, leave the wounded dying on the ground, without even trying to administer first aid. The Cleveland police bodily stopped Rice’s sister from coming to help him. On the battlefield, there are no children.

People are willing to support this mindset. Three sets of outside experts, commissioned by Cleveland prosecutors, have submitted reports saying that the Rice shooting was justifiable—that opening fire on an unarmed child, in less than two seconds, was regrettable but reasonable police work.

If the killing of Tamir Rice was reasonable police work, then the police are in the wrong line of work. Tamir Rice was a 12-year-old boy with a toy gun. He was not a threat to anyone. That is not a tragic retrospective fact about the incident; it is the entire truth of the incident.

It’s possible to watch the video and convince oneself that, in those less than two seconds, with the police shouting at him, Tamir Rice made a movement toward his waistband. Making a movement toward a waistband is a very popular excuse, among the police, for killing someone. But all that was ever in his waistband was a toy gun.

That is, when the police confronted Tamir Rice, his hands were empty. The only weapons on the scene were the ones in the hands of the Cleveland police. The only threat to anyone’s life was the police department.

Contact the author at scocca@gawker.com.