An anti-death penalty button. (Nick Oxford/Reuters)

Natman Schaye is senior trial counsel for the nonprofit Arizona Capital Representation Project.

A headline on Stephanie McCrummen’s Sept. 13 front-page article in The Post, “ An American void ,” asked: “Why do the friends Dylann Roof stayed with before the Charleston church shooting shrug about their inaction?” I can answer that question.

I am a high school dropout. I grew up in a small town in the Midwest. I spent many evenings in rundown trailers and apartments getting wasted with people whose lives were aimless. Crazy, stupid and sometimes threatening statements were not unusual. Everyone assumed they would be forgotten the next day. Acting on them was rare. Thankfully, nothing nearly as crazy, stupid or devastating as what Roof admitted to doing at Emanuel AME Church in Charleston, S.C., ever happened.

I ended up becoming a lawyer. I have represented clients accused or convicted of crimes — including capital crimes — for more than 30 years. In every death penalty case, we thoroughly investigate every detail of our client’s life. We work with experts on human development and psychology.

In every one of the scores of capital cases in which I have been involved, there were moments — usually many of them — in which someone had an opportunity to change our client’s path. Had that altered path been taken, the murder would not have been committed.

These opportunities invariably come early in the client’s life. But the opportunities also come just before the client’s downward spiral results in murder. A client may become increasingly volatile, make threats or buy a gun. But friends and relatives do nothing.

Why? Because the friends and relatives are human. Because we are programmed to believe that everything will be okay. Because the client said crazy things before but didn’t do anything. Because — like many of those people in my home town — the friends and family are too impaired, depressed or caught up in their own problems to recognize that something must be said or done. Or because they don’t know what to say or do.

These failures are not just the failure to call police when a friend or relative buys a gun and makes threats. They are myriad failures that may seem insignificant: a pregnant mother’s single night of drinking, a teacher’s failure to report suspicious bruises on a student, a coach’s cutting a player who cannot afford a uniform.

I point this out not because I claim to have the answer to how society can prevent statistically rare tragedies such as the one reportedly caused by Roof. I point it out because it is one of the many reasons that the United States must join virtually every other industrialized nation and abolish the death penalty. Capital murders occur because of countless failures not only of the killers themselves, but also of their families, neighbors, teachers and friends to act to alter the path of people like Roof.

This is not to say that murderers should not be punished for their crimes. It is simply to say that we all share at least a bit of the blame. Evil is not a rare virus that a few of us catch. It is a disease that is transmitted in bits and pieces from person to person until it accumulates and overcomes an individual. A sentence of life imprisonment without parole is a sufficient punishment for the ones who succumb.