County breaks ground on new autopsy lab, approves staff moves at coroner. Johnson County will have the beginnings of a new system for dealing with unexpected or suspicious deaths when Dr. Diane Peterson takes over next month as county coroner and medical examiner. The county commission appointed Peterson, currently chief medical examiner in Jackson County, Mo., to head Johnson County’s medical investigator team. The commission also appointed Dr. Robert Prosser, who has been county coroner for 21 years, to be one of seven deputy coroners. The appointments are part of an effort to update the county’s coroner system as the population grows. Commissioners also attended a ground breaking Thursday for the new autopsy lab. The deputy coroners will eventually be phased out as more work is done by the medical examiner staff. The commission also approved a pay increase for on-call duty by coroners from $115 to $150 per day.