This week, the nation finally learned the truth of the kidnapping, sexual assault and murder of Jacob Wetterling at the hands of Danny Heinrich ("Jacob's killer gives detailed confession," Sept 7). Upon hearing the harrowing details, we wept, knowing Jacob's final moments were filled with fear, pain and pleading. We learned that the man who killed Jacob had previously kidnapped and assaulted another boy, Jared Scheierl. We raged, knowing that for 27 years Heinrich enjoyed a freedom he did not deserve and, we hope, will never again possess.

Heinrich committed these atrocities in 1989, when U.S. child sexual abuse rates were at their highest. Since that time, these rates have fallen by about half. Those of us who have spent our careers studying child sexual abuse cannot pinpoint the precise reasons for the reduction, but they likely include increased awareness of child sexual abuse and the harm it causes, as well as increased sentence durations for convicted offenders.

As a nation, we respond to child sexual abuse reactively, with policies that are triggered only after a child has been harmed. Many of these policies are predicated on particularly heinous offenses. Indeed, it was the abduction of Jacob that helped spur sex offender registration and public notification policies.

But cases that involve the "worst of the worst" are also the "rarest of the rare," and unfortunately laws based on them tend to fail. Such is the case for sex offender registration and notification, which research has shown largely fails to improve community safety. The same can be said for sex offender residence restrictions.

Even if these policies were effective in reducing reoffending, they do nothing to protect children from first-time offenders, who are the vast majority of perpetrators. The erroneous belief that all sex offenders are the same — that anyone who even considers sexually abusing a child is a potential Danny Heinrich — has led us to structure our responses around detection, punishment and surveillance of known perpetrators. We put almost no resources into primary prevention efforts. Our failure to see child sexual abuse for what it is — a preventable public health problem as well as a criminal justice problem — ensures that children will continue to experience abuse.

We need to recognize that, like every other form of violence, child sexual abuse is an avoidable tragedy. We need to ensure that real resources are directed to the thoughtful development, rigorous evaluation and broad dissemination of effective prevention programs. Several of us in this field have been working on such programs, one of which targets young adolescents with clear messaging that it is both harmful and illegal to involve younger children in sexual behaviors. Another will provide help and guidance for adolescents who find themselves with an attraction to prepubescent children. Still other programs target parents and educators to help them promote the healthy sexual development of children. There are many other ways to prevent child sexual abuse — these programs are only the beginning.

We are fortunate to raise our children in a time when rates of child sexual abuse are at their lowest. We should take this opportunity to work even harder to eliminate child sexual abuse altogether.

Imagine how our world would look if, instead of waiting for offenders to be caught, we developed effective programs to ensure that people don't become offenders in the first place. That is the promise of public health. That is where our policymakers and the rest of us who want to end child sexual abuse should now invest our efforts and resources.

Elizabeth J. Letourneau is associate professor and director of the Moore Center for the Prevention of Child Sexual Abuse at Johns Hopkins Bloomberg School of Public Health in Baltimore.