A Rapid City man has died after he was found unresponsive at the Pennington County Jail Saturday. According to a release from the Pennington County Sheriff’s Office, the Division of Criminal Investigation is investigating the death of 31 year old Richard Zimmerman. An autopsy is being conducted. Zimmerman was arrested on a parole violation Friday. The next morning he was found unresponsive and the jail medical staff started resuscitation efforts before Zimmerman was taken to the hospital where he was pronounced dead.