I know three women whose sons are in prison, two for having committed murder.

These women are intelligent, kind, wise to the ways of the world, contributors to society. They look to me, each one of them, like they had to have been very good mothers. They seem wholesome and cheerful, exemplary, what anyone would want in a mother.

True, maybe each one was evil behind closed doors. Sure, we can’t tell the whole story by looking at someone. Of course, we can’t judge a book by its cover. And Lord knows, we all have our covers. All of us mothers have our public selves and our private selves. And we are different mothers to different children. The mother of the first born child is a different mother than the mother of the third or fourth or fifth. We age, we change, we modify ourselves and our thinking. In the end, each mother has a thousand permutations. Even so, these three women have always seemed to me to be solid, clear-headed, compassionate mothers.

So what happened?

I don’t know.

I do know that I’ve imagined myself in their shoes more than once. And not because my sons were violent or criminal. They were just boys, then teenage boys and then young adult men and every time the phone rang late at night, I was paralyzed with fear that something terrible had happened. That they had caused something terrible to happen.

Were my fears unfounded?

Yes, I guess they were. But that’s probably what the three women I know whose sons are in prison thought as well. And Dylan Klebold’s mother, Sue Klebold, thought. She saw herself as a normal, run of the mill, mother with a normal, run of the mill, son until he wasn’t, something she only knew after the murders her son committed at Columbine.

I remember, in 1999, the rush to blame her. The thinking, which is almost always the thinking when something goes wrong with a child, was that something terrible had occurred with his upbringing. His mother had to have done something wrong because if she did something wrong and we can figure out what that was then we can avoid doing that thing and avoid having our child murder a dozen beautiful young people in a school library on an April afternoon.

The painful possibility is that maybe Dylan Klebold’s mother didn’t do something wrong. If we think that, though, we enter the world of random occurrence, the sickening, head-spinning world of “Anything Can Happen.” None of us wants to go there so we keep looking for causes and reasons, things we can avoid, ways that we, as mothers, can be more perfect, make even fewer mistakes.

I’m buying Sue Klebold’s book tonight, A Mother’s Reckoning, and I’m willing to bet I finish it tonight as well. The light from my Kindle will glow in the dark of our bedroom, my husband asleep next to me, peaceful, no longer any danger of the phone ringing with bad news. My sons are grown, adults who work out at the gym and watch Food Network, teach their kids to ice skate and show up to work every day. The days of my intense, possibly misplaced, fear are over. But when I read this book, it will all come back to me, my praying that my sons will grow up unharmed and without harming anyone else. And I’ll feel a strange sisterhood with Sue Klebold because I know all of us, as mothers, live on a razor’s edge.

Some of us understand this better than others.