The bigger question at the moment, the one that will bring out the worst in at least a few people who try to answer it, is whether or not the attack constitutes a hate crime. The (black) teenagers hurled epithets at their (white) victim, attacking him for the color of his skin and associating him with the country's most famous white supremacist who will also soon become the most powerful man in the world. There's also a suggestion that the attack constitutes a hate crime because the victim had special needs, although there haven't been any quotations from the video that back that up. If the victim was attacked for being white, we'd have a problem, because black people are oppressed in our society and white people are not. If the victim was attacked for having special needs, we wouldn't have as much of a problem, because people with special needs are oppressed in our society and people without them are not. When the Democratic Party was pushing for hate crime legislation in the 1990s, this was not the case they had in mind.
The investigators are trying to figure out the central motive behind the crime. Their reticence suggests a truism. Humans are complicated moral actors and they perform wicked as well as good deeds due to a variety of interweaving and sometimes contradictory motives. Hate crimes, crimes in which the primary motive is clearly related to the victim's membership in an oppressed group, are real. But in most hate crimes, as in most crimes, there are a riot of factors. Did he kill the black kid at a gas station because he just couldn't deal with godawful rap music interrupting his otherwise good day? Did they crucify that gay kid because they were panicking over their own masculinity or because that drug deal went south? A combination of those factors and probably several more. Did these kids attack the white boy with special needs because they needed to please one another, because they were afraid of what they thought of as an imperfect body or imperfect mind, because they saw him of all the white people in the world, in a twisted way, as their oppressor? Did they wish to pick on the weakest member of an opposing tribe during a moment of peak racial tension to make a point? When we become bad novelists or armchair psychologists and isolate the attack to a single motive we are effectively punishing thoughts not actions.
One of the strongest provisions of hate crime legislation are prohibitions on attorneys from employing arguments that would defend the idea of hate crimes. "My client, like many of you, is afraid of men in high heels. Surely, you can understand where he was coming from?" One of the weakest are the requirements for stiffer penalties on the grounds that a hate crime doesn't just attack an individual but all members of that individual's group. Those stiffer penalties satisfy society's sense of moral decency, allows it to contain the evils of bigotry within one complicated human actor. They don't prevent hate crimes.
I'm writing this while a young sociopath is on trial for opening fire on group of sweet black churchgoers, members of one of the most important sites in civil rights history. Dylan Roof has offered no means to claim he had anything other than racism in his heart. So, yes there are hate crimes that don't deserve further, deeper examinations of the criminal's motives. But in the end, I can't see how the blunt instruments of the American legal system could sort out the psychology of most of those who commit hate crimes.
If you absolutely still believe in hate crime legislation, and all of its provisions, I will make one final suggestion. If you want to see a society with less racism, ableism, homophobia, transphobia, and misogyny, wouldn't figuring out a way to reform people who commit hate crimes be a priority? And wouldn't figuring out how that hatred fits with so many other factors be worth studying? And, if so, doesn't restorative justice rather than stiffer penalties sound like a better means of getting to where we want to be?