Do you know where your local sex offenders are?

TRI-CITIES, Wash. -- It's the middle of summer. Do you know where local sex offenders are?

Parents like Julie Roach would like to think they do, but more often than not, dangerous sex offenders are falling through the cracks.

"That's really worrisome as a parent," Roach says. "I certainly don't want to know that there's people out there that can't be kept track of."

By law, a sex offender is required to tell police where they live. But last year, roughly 50 sex offenders in Benton and Franklin Counties changed addresses without telling authorities -- meaning some of them could move into your neighborhood without you knowing it.

"It makes you think a lot more about keeping your kids supervised," Roach says.

In the last three years, the number of non-compliant sex offenders has doubled in the Tri-Cities. As a result, police beefed-up communication... And turned to the community for help. That vigilance has gone a long way at hauling criminals to justice. Of the dozens of non-compliant sex offenders last year, police eventually caught and arrested all of them.