BROOKLYN - New York State has launched a new alert system that allows residents to track registered sex offenders in their neighborhood.

With more than 4,000 level two and level three offenders living in New York City, residents can receive instant messages when one of those predators moves into or out of their zip code.

The system is free and allows people to register several locations. Residents can sign up online with the state Division of Criminal Justice Services and choose to have alerts sent by email, phone, text message or fax.