Mare of Easttown ending explained: Who killed Erin McMenamin? Why that crushing reveal had to happen

*Warning: Obviously this article contains spoilers from the finale of Mare of Easttown season 1

Who killed Erin McMenamin? Mare of Easttown viewers finally got their answer last night as it was revealed Ryan Ross was the murderer with the entire Ross family helping to cover it up.

The gripping season one finale opened with the bombshell that it was John Ross who had been having the incestuous affair with the teen and that he was asking his brother Billy to take the blame.

With all the signs pointing to John being the killer, he managed to explain everything that happened that night – but was noticeably missing information about the vital murder weapon.

When it appeared the case had been solved, mare soon realised who really had the murder weapon that night – John’s 13-year-old son, Ryan.

Ryan found messages on John’s phone from Erin and in a desperate attempt to bury their secret and keep the family together, stole Mr. Carroll’s gun to scare Erin into retreat.

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However, after trying to shoot her through the hand he accidentally shot her in the head.

Ryan asked John for help, who turned to Billy – hence why he was spotted cleaning the blood-soaked clothes.

Lori learned the truth and on John’s advice lied to Mare to try and push the detective, and her best friend, to charge Billy.

Eventually, Mare put the pieces of the puzzle together.

Writer and creator Brad Ingleby explained why the killer had to be Ryan all along.

Lori had been by Mare and by her side and now Mare has to reciprocate in a way that’s challenging

‘I knew that we had to have a good ending that had to be emotional and surprising,’ he told Decider. And so it just hit me one day. I was like, “Oh, what would be the hardest journey that Mare would have to go on in the show?” And then it became clear. “Oh, it has to go through Lori, the best friend; it’s the devastation of her son.”

‘And it just felt like in terms of themes of the show — Mare losing a child and Lori losing a child and mercy — it felt like, wow, that would be really potent emotionally if it had to be Lori’s child. Because Lori had been by Mare and by her side and now Mare has to reciprocate in a way that’s challenging.

‘So it took a little while to land on that but I wouldn’t start writing until I knew where it was ending because I knew it was going to be challenging to craft all the surprises along the way.’

Mare of Easttown is available to stream on NOW.

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