Chrissy Teigen & Toxic Femininity Mamamia Out Loud ADVERTISEMENT Mare of Easttown: Looking suss, John. Image: Binge. John Ross knows a lot more than what he's letting on. The man has been acting pretty damn suspiciously this whole time. We know he's a cheater and a liar and even if Billy was the killer, he was prepared to cover it up. John could be the killer for several reasons. He may have had an ongoing relationship with Erin (which given Erin's age, would have been statutory rape, not to mention incest), or raped her at the family reunion, and is the father of her son DJ.