We Finally Know Who Killed Erin McMenamin on 'Mare of Easttown'

Big spoilers ahead for the Mare of Easttown finale. Proceed with caution.

If you just finished watching the Mare of Easttown finale, let’s take a moment to collectively decompress. After seven weeks, HBO’s Kate Winslet-starring murder mystery came to a thrilling close tonight, answering two major questions: Who killed Erin McMehamin, and who is her baby’s real father? Sure enough, each answer points to a different person.

Let’s start with baby DJ’s real dad: It’s John Ross (husband of Mare’s best friend, Lori Ross, and brother of Billy Ross). The photo Jess Riley showed to authorities in the previous episode, which she dug up from Erin’s diaries, shows John and Erin in bed together. Under police custody, John admits that he started an affair with Erin during the 2017 family reunion. From then on, they started “hanging out” (read: having sex). John explains that their relationship wasn’t just physical; they leaned on each other emotionally while going through a “tough time” in their lives. They confided in each other, talking via prepaid phones to hide their correspondence from John's wife. When Erin got pregnant, John asked her to get an abortion, but she didn’t. Dylan Hinchey, Erin’s boyfriend at the time, just assumed the baby was his own.

During the interrogation, John confesses to killing Erin, and is later sent to jail. But he wasn’t actually the murderer; he was covering up for someone else. Erin's real killer is John’s teenage son, Ryan Ross.

Ryan was distraught to hear that his father was in an affair again; he discovered John’s relationship with Erin after finding their texts to each other. The night of Erin’s death, Ryan, John, and their family were at Frank Sheehan’s engagement party. Ryan saw his dad on a tense phone call in the middle of the event, then later found texts from Erin on John’s phone, asking him to meet her at Brandywine Park at midnight. Desperate to keep his family together, Ryan planned to intercept Erin at the park and threaten her to stop seeing his father. He biked to Glen Carroll’s house and stole his gun—a Colt Detective Special—from the shed. (Ryan has access to the lock because he cuts the Carrolls’ lawn.) Ryan waited at the park until Erin was dropped off by Deacon Mark. He surprised her at gunpoint, telling her to “stay away from my family.” Erin tried to wrestle the firearm out of Ryan’s hands, but in the scuffle, the gun went off twice and killed her.

Ryan got scared, called John for help, and returned the gun back to Mr. Carroll’s shed, now with two rounds missing from the weapon. John and his brother Billy cleaned up the mess; they planted Erin’s body in Sharp’s Woods because she was there with other people earlier that night. The Rosses wanted to make it seem like one of the kids murdered her.

Lori, Ryan’s mom, was in the dark about this family secret until John told her the morning he and Billy went to their dad’s fishing cabin. When Mare came later that day, Lori lied to protect her son and said Billy killed Erin.

If you’re still reeling from all of those bombshells, you’re not alone. Here’s what other viewers had to say.

Of course Stephen King guessed it right.

All seven episodes of Mare of Easttown are now streaming on HBO Max. Watch Now

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