On EP 17 Hotel Assassination Kelsey tells Sierra about career criminal, James Earl Ray and his connection to the murder of a well know leader in the 60's.

Sources: 
https://en.wikipedia.org/wiki/James_Earl_Ray
https://www.nytimes.com/1998/04/24/us/james-earl-ray-70-killer-of-dr-king-dies-in-nashville.html
https://www.illinoistimes.com/springfield/Content?url=https://illinoistimes.com/article-4612-the-assassin%25C2%2592s-brother.html
https://web.archive.org/web/20080524142603/http://knoxville.fbi.gov/hist.htm
https://www.nytimes.com/1998/03/28/us/third-inquiry-affirms-others-ray-alone-was-king-s-killer.html