Sex offender registries are designed to allow law enforcement and the public to keep track of those who may re-offend. But across the country, there are high-risk sex offenders who have not registered and authorities have no idea where they're living. Matthew Lee Aiken is one of them. He was convicted of indecent assault and battery on a child, but failed to report his address. Police and the public had no idea where he was. Chief Investigative Correspondent Lisa Guerrero tracked him down.