On 31 May, in Milwaukee, Wisconsin, a 13-year-old boy named Darius Simmons was allegedly shot to death by 75-year-old John Henry Spooner, right in front of the boy's mother, Patricia Larry. Spooner had confronted Darius as he was taking out the trash and accused the kid of stealing from his home. When Ms Larry attempted to defend her son verbally against the accusation, Spooner drew a 9mm handgun.

Darius, who had been in school at the time of the theft and who was, by all accounts, was a well-behaved, outgoing sixth-grader, denied any wrongdoing. Spooner, unconvinced, reportedly raised his firearm and shot Darius in the chest at close range. Though fatally wounded, Darius attempted to escape and turned to run, while Spooner continued to unload, aiming for the boy's back. Darius collapsed on the pavement and Larry, who had watched this episode unfold in horror, ran to her child to see if he had a pulse. Darius was dead.

Spooner was known by his neighbors, police, and local elected officials as a gun collector. In a recently reported burglary, Spooner claimed that four shotguns were taken. The police had already done an investigation, several days prior, to burglaries at Spooner's residence. They had interviewed Darius Simmons' family, and concluded that no one from his household was involved. Larry, Darius's mother, had lived in that home for only a month.

After police arrived, Darius's body remained on the sidewalk, while his mother was questioned in a squad car for approximately two hours. During the investigation of the shooting, they searched Larry's home again. Finding nothing relevant to the homicide, they nevertheless proceeded to arrest Darius's older brother on account of truancy tickets.

In contrast, members of Spooner's family were reportedly allowed to re-enter their home and remove "items" – despite it being part of the crime scene. Spooner himself was granted bail for $300,000 (meaning that only $30,000 would have to be posted for him to be freed). Appearing in court Monday 11 June, Spooner pleaded not guilty to first-degree intentional homicide.

There are many ways to view this latest chapter of American race relations. One dimension of the story is that Larry had moved to this so-called white section of Milwaukee because she wanted to give her family better educational opportunities and the chance to escape the risks of inner-city violence (in a manner not unlike the way the parents of Trayvon Martin had moved to that gated community where he was murdered). I understand this because my mother did the very same thing with me when I was Darius's age. I was certainly called the N-word by the good white folks who "welcomed" us to the neighborhood, but no one thought to pull a gun and shoot me.

Another way to view this is that Milwaukee, like most urban centers in America, is scarred with violence. Blacks and Latinos piled into ghetto dwellings, with limited educational, employment, and life choices, do definitely commit horrific acts of violence against each other. I see this every day in my own neighborhood of Brooklyn, New York. But because such violence does occur does not mean that a George Zimmerman, in Florida, or a John Henry Spooner, in Wisconsin, has a right to arm himself to the teeth and become a de facto law enforcer, who demonizes every single black or Latino young male they encounter.

Rather than address the root causes of crime and violence in America, we point fingers, we cast blame randomly: we shoot to kill, we ask questions later. But that is the climate of America: if you are a black or brown person, you are a criminal suspect – the culprit for every societal ill – even if you have nothing to do with those problems.

In Wisconsin, Republican Governor Scott Walker has just survived a bitterly divisive recall election, occasioned by his controversial anti-union law. This same Governor Walker also approved a conceal-and-carry gun law in his state – as if the vigilante tendency needed any encouragement.

Finally, it pains me to see yet another mother, another black mother, posing with a picture of a dead son, gunned down before he had a chance to live. No doubt, she will have to listen to the arguments of Spooner's attorneys, casting him as a victim of crime. Perhaps she will even be forced to hear doubt cast on her dead son's reputation.

We have been here before. And we will be here again. Unless we Americans can have real, honest, and serious conversations about race and racism in the US, we are condemned to repeat the dehumanising lies that poison our community relations and cause the endless-seeming cycle of deaths like Darius Simmons's.