Documentaries can cover a wide array of subjects, but perhaps the most notorious of them cover true crimes and world events. Most documentaries seek to aim a spotlight on wrongs, whether that means bringing the truth behind a murder case to a wider audience or pointing to accomplices missed by the judicial process.
In fact, several documentaries have aired and garnered a new set of eyes at a police station to reopen a case. Some have presented evidence that wasn't provided to the original investigators due to science restrictions at the time or other roadblocks to gathering clues. Several times, documentaries have presented new theories about cases that turned out to be just what was needed.