When I visit the county jail, on Wednesday nights, there is never a time when I feel afraid or threatened. Of course, officers in the control room watch our every move and each volunteer wears an alarm for emergencies. The alarms work very well, by the way. We tend to be careless and set them off from time to time.
But my sense of security comes from another source. Christ calls us to visit him in prison (Matthew 25:36) and I believe he is there when we answer the call.