It is the randomness of the Mont Vernon murder that disturbs us so, and not just that the victim's home was picked with casual coldness. It could have been your home that was targeted, your child who barely survived, your spouse who is dead, hacked to death by machete in her bed during the predawn hours by a gang of teenagers while her husband was away on a business trip.

Add to this the non-random actions of the alleged assailants: Selling jewelry stolen from the home for $200 at the Pheasant Lane Mall later on the day of the killing, showing up at school the next morning as though nothing had happened, posting on Facebook about having had such a great time.

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There is another randomness about the murder that may be even more deeply disturbing for anyone who works with teenagers or any parent who has held a baby and wondered what kind of adult the child will become, and that is the knowledge that there is at least a chance that any child, regardless of the quality of his or her parenting, could grow up to one day commit such a heinous act.

Ted Bundy, Timothy McVeigh and the Columbine shooters were all monsters who had mothers. The same child you loved without condition -- feeding him as an infant, kissing boo-boos and holding hands while walking to the school bus stop -- could get so far off on the wrong track that he ends up held for murder while still in his teens.

The four young men ages 17 to 19 charged in the Mont Vernon murder seem to have had basically normal upbringings. There were youth sports, acting in school plays, years in the Boy Scouts. They were raised in affluent towns known for great schools.

With adolescence came every escalating element of a parent's worst fears: hanging out with the wrong crowd, driving recklessly in cars, drug use, getting arrested multiple times, getting a girlfriend pregnant, dropping out of school. Until, ultimately, he is held without bail for murder. Short of being the parent of a victim, does a parent's nightmare get any worse than this?

"Ever since my son met Stevie in April, we've been back and forth to this courthouse four times," the father of one of the four charged in the crime told a Union Leader reporter last week, speaking of the gang's apparent leader. The father described his son as easily influenced, easily led, and told of spending the night of the murder texting his son until 4:30 a.m. in a futile effort to find out where he was. It's not hard to imagine that this was not the first night the father had stayed up worrying about what his son was up to.

How does it come to this? How does a kid who seems to be on the right track get onto the wrong track? How do parents whose kid falls in with troublemakers get their child back out? What do you do when your daughter starts dating one of them, as happened to another family caught up in this mess? The father of that girl acknowledges feeling threatened by his teen daughter's boyfriend. Put yourself in that dad's shoes and imagine the constant dread he lived with since the young man arrived on the scene.

Some might assume all the adults involved were lousy parents and the kids came from less than ideal homes. Even if that were true, so do lots of kids who don't end up sociopaths. More likely, the parents were like most of us: imperfect but doing the best we know how, and doing the job well enough to shepherd most kids safely to productive adulthood.

Good parents will sometimes raise a child who does terrible things. It's a timeless phenomenon referred to in the Bible as the bad seed. The four young men are responsible for the decisions they made, choices to kill and to go along with the plan. That's not the parents' fault.

You don't have to be a Souhegan Valley resident locking doors that used to be left unlocked at night or considering whether to buy a dog, a security system or a gun to know a sense of profound worry that you could be next.

All you have to be is a parent. And for many, that's just as frightening.

Fergus Cullen, a freelance columnist for the New Hampshire Union Leader, can be reached at fergus@ferguscullen.com. Donations to assist the victim's family can be sent to the Kim Cates Memorial Fund at St. Joseph's Hospital, 172 Kinsley St., Nashua, NH 03061.