Georgia:

‘Hitman’ Gary Krueger

Episode sources:

1. Unsolved Mysteries with Robert Stack —Season 12 Episode 4

2. True Crime Diary by Michelle McNamara

3. ChinookObserver.com article by Natalie St. John

4. KIRO7.com article by KIRO Team 7 Investigative Reporter Chris Halsne

5. Unsolved Mysteries Fandom Site

6. Unresolved Mysteries thread on Reddit 

Karen:

Gerald and Charlene Gallego

Episode sources:

1. Gerald and Charlene Gallego Wikipedia

2. Gerald Armond Gallego Murderpedia

3. The Sex Slave Killers thread on Reddit

4. CBSlocal.com article by Maria Medina

5. SFgate.com article by Joan Ryan

6. Radford University Department of Psychology Summary of Charlene by Kelsey Inscoe and Tina Gauldfeldt

7. Radford University Department of Psychology Summary of Gerald by Jordan Christensen, Crystal Cobb, Nina Critz, & Christine Miles