35. The Grim Sleeper: Serial Killer Lonnie Franklin Jr.

In the mid-1980s in south central Los Angeles, a string of murders is connected, but the killer is elusive and is able to get away for a while. After a period of decades during which investigators believed he was no longer active, a new series of murders breathes life into their investigation once again, and they're able to use genealogical testing to narrow down their suspect list and finally catch the Grim Sleeper. 

Sources: 

https://en.wikipedia.org/wiki/Grim_Sleeper

https://www.aetv.com/real-crime/grim-sleeper-serial-killer-victims

https://clkrep.lacity.org/onlinedocs/2010/10-1234_CA_07-21-10.pdf

https://en.wikipedia.org/wiki/Margaret_Prescod

https://en.wikipedia.org/wiki/Watts_riots

Cunningham, Chad & Wendy Greene (directors). Mark of a Serial Killer, season 3, episode 7 The Grim Sleeper, 2021.

Drew, Victoria (director). Evil Among Us: The Grim Sleeper, 2024.