Serials have a deep history from early radio and pulp magazines. They are stories told in multiple installments; by their nature they allow for deeper insights and details. An honorable mention, albeit from a different medium, is the excellent podcast series hosted by Sarah Koenig of This American Life, entitled Serial.
The Keepers (2017) is a 7-part mini-series documentary produced by Netflix and directed by Ryan White. A Facebook group started by former high school students helped to revive the investigation of their beloved teacher’s unsolved murder from 1969. The Keepers is thorough, and it unearths many unexpected revelations.
Making a Murderer (2015) is a 10-part mini-series documentary produced by Netflix and directed by Moira Demos and Laura Ricciardi. Steven Avery was falsely imprisoned for rape and attempted murder before being exonerated 18 years later with DNA evidence. The series chronicles that history and the dramatic events to come.
O.J.: Made in America (2016) is a 10-part mini-series documentary produced by ESPN and directed by Ezra Edelman. Even if you lived through the O.J. Simpson trial in the 1990s, this comprehensive documentary sheds a lot of light on the events of that period as well as his overall life. It is very well done, which makes the revisit much more palatable.