This heavily researched piece describes the most effective means of preventing repeated sexual offending: Welcome the offender back into the community.
Here is an excerpt:
. . . according to a major 2014 report on sex offender management commissioned by the U.S. Department of Justice, registries have “mixed” results. And while residency restrictions offer communities a sense of security, they don’t appear to have much effect. In 2008, Iowa’s Department of Criminal and Juvenile Justice Planning declared that the state’s residency restrictions had served little purpose. The 2014 national report recommended against the use of such restrictions. “They don’t work in protecting children or preventing recidivism,” says Jill Levenson, a former Child Protective Services investigator who researches sex offender legislation at Barry University, near Miami. “All the laws really do is regulate where somebody sleeps at night, but they really don’t regulate where a sex offender might go during the day.”