Nearly a third of the Arizona's high-risk, registered sex offenders were unaccounted for at some point during 2012, raising questions about the state's system of tracking and monitoring sex offenders, a newspaper reported.

An Arizona Republic analysis of nearly 5,700 high-risk offender registrations found large concentrations of offenders in the central areas of Arizona's two largest cities.

About one-third of these high-risk offenders had an unverified address at some point during the seven months the Republic conducted its analysis, meaning authorities could not report precisely where they were.

Nearly 200 offenders were homeless statewide as of Nov. 7, many registered to street corners or intersections close to homeless shelters, where they have access to social services but can no longer stay overnight.