In the days after Eric Harris and Dylan Klebold rampaged through their high school here, the rush to assign blame had seemingly resulted in a clear verdict.
Bombmaking materials were in plain sight at one home. One of the boys left a sawed-off shotgun on his bedroom dresser. Both teens openly admired Hitler and were fascinated by violent video games.
Surely the parents must bear much of the blame, people said.
But as Americans rethink the appropriate boundaries of parental control, many parents and legal experts say that holding mothers and fathers culpable may not be easy - or fair. The line between teen angst and a darker desire to kill or destroy can often be difficult to discern, even in the closest of families, they say. And even if parents are attentive, there's only so much they can do.
Still, with many politicians and law-enforcement officials calling for tougher laws, the Littleton shootings may create a new legal and moral standard for how much control parents should keep over their children.
"There is a difficulty for parents to distinguish what is normal adolescent resistance to control from what isn't," says Delbert Elliott, director of the Center for the Prevention of Violence at the University of Colorado in Boulder. Evidence suggests Eric's and Dylan's parents "should have been more knowledgeable" about their sons' behavior, he says. But it is possible they didn't see the warning signs.
In fact, many others - from teachers to school counselors to juvenile officers - apparently missed clues that Eric and Dylan were on a road to destruction. Three months ago, a court officer wrote glowing reports of the two when they completed 45 hours of community service after a car-burglary arrest.
What the parents did know may determine whether local authorities file criminal charges, says Mark Paulter, chief deputy district attorney in Jefferson County. If the parents knew about the weaponry in their homes and had reason to suspect the boys' capacity for violence, they could be charged as accomplices or with negligence. So far, authorities say the parents have been cooperative. By law, though, they are not obligated to supply information.
If investigations discover that the parents ignored evidence of of guns and explosives in their homes, Colorado Gov. Bill Owens has said "perhaps charges will be filed and certainly should be filed." US Attorney General Janet Reno added that it's important to identify what the parents "knew or should have known and take appropriate steps."
The movement to hold parents more accountable for their children's misdeeds has been progressing nationwide in recent years. At least 15 states have passed laws holding parents liable for the criminal acts of their children. And many more states - including Colorado - have parental-responsibility laws that make parents civilly liable for damages.
In an Illinois case filed last week, the parents of seven teenagers accused of stealing $90,400 from a suburban bank are being sued by the bank for damages. The bank maintains that the parents have a responsibility for the crime, even though they knew nothing about it.
And in Jonesboro, Ark., where two boys shot four classmates and a teacher last year, the victims' families are suing the parents of the killers, the makers of the guns they used, and one boy's grandfather, who owned the guns.
BUT pressing criminal charges against parents has never been attempted in the wake of a school shooting. And crossing that threshold may cause a host of problems, some observers say.
Adolescence is a time of rebellion and separation from parents, sociologists say. Not only may parents have a blind spot to their children's defects, but teens are also notoriously adept at hiding things from adults. "I certainly didn't go into my son's bedroom on a regular basis," says Mark Soler, president of the Youth Law Center in Washington - and father of a teenage son now in college. "He could have hid things in there that I wouldn't have known about," he says. "I think it's a very difficult issue."
Under civil law, parents already can be liable for what they don't know. "The standard is basically: Did the parents know or was there so much information available that they should have known?" explains Mr. Soler. It gets complicated because there also needs to be proof that the parents' negligence was a causal factor to the crime. "That legal issue is very hard," he says.
Yet the assumption that parents can keep their kids from screwing up is itself problematic, say others. Longtime friends and neighbors said the Klebolds and Harrises were caring families. They played hoops together in their suburban driveways, attended Little League games, and enjoyed outdoor family vacations. There have been reports, though, that Eric had been on psychiatric medication.
"Sometimes parents do all the best things in the world, and they can't control their offspring," says Harold Krent, a law professor and associate dean at Chicago-Kent College of Law.
While holding parents accountable does supply "more incentive for parents to look over their little ones," ultimately, the approach is too simplistic, he says. "You may know your kid is tough; but do you really know that your child is going to throw a rock through a window, or commit a specific crime?"
Besides, even when parents do sense trouble, they can't direct all aspects of their children's thoughts and behavior, he says. They can't police every influence on their child - from movies to magazines to video games - and with an already difficult teen, too tight a rein can just exacerbate problems.
For his part, Governor Owens, in his weekly radio address, urged parents to play a more active roles in their children's lives. "Do you know if your child has a [Web] page?" he asked. "Do you know what is on your child's home page, or whom they talk with on the Internet? If not, please find out."