Zodiac (2007). Based on true events surrounding the long investigation into the notorious Zodiac killer who sent detectives and federal investigators cryptic codes and letters containing vague hints about his future plans to hunt down more innocent victims. Finding this man is nearly impossible, as he leaves no solid evidence linking him personally to any of his crimes, and any evidence that is eventually found is all circumstantial evidence which is not admissible as evidence to prosecute. To track this spook down takes a lot of time, research and dedication.

After a decade long investigation leading almost nowhere, a San Francisco cartoonist, who became obsessed with tracking down the Zodiac Killer willing to put his career aside to find out who exactly this killer was, offered to help former and current investigators identify the Zodiac killer. They came real close to solving this case, even determining who the real murderer actually was. Although the case was close to being solved, the most likely suspect of the case died from a heart attack in 1992.

Editor's note: although there have been many other suspects, this case has never been officially solved and there are still debates today about who the killer really was. Some independent investigations still continue today, all unsolved.