In the first part of this two-part episode Caroline tells Jane about the despicable Pam Hupp. When Betsy Faria is found brutally murdered in her own home, police immediately suspect her husband, Russ, despite the fact that he has an alibi for the time of the murder. The focus on Russ allows the truly evil actual murderer, Pam Hupp, to hide in plain sight.

Sources:

https://www.stlmag.com/longform/pam-hupp/

https://www.stltoday.com/entertainment/television/the-thing-about-pam-the-truer-story-behind-nbcs-true-crime-miniseries-about-pam-hupp/article_e2e3d63a-88f1-5f98-9f39-7215d5b77d92.html

https://fox2now.com/news/pam-hupp/the-real-truth-about-pam-hupp-3-deaths-2-questionable-investigations-1-woman-at-the-center/