Criminal justice includes the fields of policing, prosecution, court, and judicial administration; adult probation, parole, and custodial correctional administration; juvenile justice administration; and various public services to assist victims, witnesses, and criminal defendants. Most agencies and organizations involved in American criminal justice are governmental, but private commercial and non-profit, non-governmental organizations also are involved in American criminal justice. The private investigator, so well known from television and the movies, and the highly visible uniformed private security firms doing business in communities are the most conspicuous representations of private law enforcement. In detective fiction, they are often loners like Sam Spade or Philip Marlowe, maybe having a partner or two and a secretary. The prosecution function includes submission of criminal charges and supporting evidence to grand juries and preparation of cases for trial. The defense attorney performs several roles before, during, and after trials. In addition, attorneys develop personal styles.