Search for Pennington County, SD registered criminal or sex offenders in your neighborhood. View sex offender registry info and criminal records for Pennington County, SD registered offenders. Busted! Sex Offenders - Find Offender Information for Rapid City, South Dakota. Rapid City, South Dakota Offender Search Database. Rapid City, SD Attorney General Larry Long said the Pennington County Web site is the first in the state to be linked to the state's sex-offender.