Mare of Easttown Theory: Who REALLY Killed Erin (Not Billy)

Warning: Spoilers for Mare of Easttown Episode 5 and 6 

The penultimate episode of Mare of Easttown appears to have solved the case, with Billy Ross ready to confess to Erin’s murder, but there’s evidence to suggest that John Ross is the one behind Erin’s death, not Billy. HBO’s limited series stars Kate Winslet as Mare Sheehan a local detective in a small Pennsylvania suburb of Philadelphia. The series follows Mare as she investigates the kidnapping of Katie Bailey and the murder of Erin Ross.

As the show progresses, the list of murder suspects grows. Throughout the season, fans have suspected that John and Billy Ross knew more about Erin’s murder than they were letting on, and this theory comes to a head in the penultimate episode. By the end of the episode, Mare has managed to rescue Katie from her kidnapper — who she and detective, Colin Zabel (Evan Peters) are able to track down in Mare of Easttown episode 5 after the kidnapper takes a second victim. Meanwhile, Erin’s cousin, Billy Ross is the primary suspect in her murder. But with one episode left, the series may be saving its final twist for the season 1 finale.

At the beginning of Mare of Easttown episode 6, Billy is in a confrontation with his father and brother. He says that he’s angry with John for cheating on his wife, claiming that he’s lashing out at him because “no one ever holds him accountable for anything.” This statement provides a clue that there’s more to the story than John’s alleged cheating with Sharon. It could be that Billy is keeping an even darker secret for his brother. By the end of the episode, the audience has discovered that someone from the Ross family gave Erin a locket engraved with the date of the Ross Family Reunion, which is presumed to be when Erin’s affair with DJ’s father began. Although Billy confesses to Erin’s murder and claims to be DJ’s father, there is evidence to suggest that John Ross is DJ’s real father and that this secret got Erin killed.

Why John Ross (Not Billy) Is More Likely DJ’s Father

In Mare of Easttown episode 5, “Illusions,” Lori is completely blindsided when she finds out John is cheating again. She tells Mare that the first time it happened she sensed it, but not this time. Maybe that’s because John and Ryan are keeping an even darker secret from her. Since he’s cheated before and lied about it to his family, John seems more likely capable of having an affair with Erin than Billy, who is generally a more reserved and insecure character. Not someone capable of seducing his teenage niece and getting away with it. It’s more believable that John is the real father of Erin’s baby. There’s also Ryan Ross’s involvement to consider. His behavior at school and acting out shows that he’s clearly distraught about something. It’s possible that Ryan Ross knows the truth about Erin’s murder and that’s the real secret he’s keeping from his mother. While Lori assumes John’s affair is with Sharon, her son doesn’t give her any details and John never confirms or denies this either. John and Lori are never shown discussing his affair, and after he tells his father that Lori thinks he’s having an affair, John deliberately avoids confirming whether or not it’s true.

John Is Manipulative & Billy’s Confession Feels Coerced

After their dad tells John about Billy coming home covered in blood the night of Erin’s murder, Billy’s subsequent confession to John feels forced. Viewers are brought into the scene mid-conversation, so it’s difficult to know exactly what has been discussed. But John is adamant that Billy proclaim himself as Erin’s killer.  Meanwhile, Billy barely seems to believe the words he’s saying. While Billy likely knows who killed Erin and helped clean up the crime scene — which would explain why his father saw him covered in blood — that doesn’t necessarily mean that he’s the one who killed Erin. John is clearly the dominant one in their relationship. And already know that John is willing to lie and manipulate other people, which becomes obvious when it is revealed that Ryan has had to cover up for his father’s affairs in the past. The scene where  John is “comforting ” Ryan about the secret they are keeping further demonstrates John’s deceitful nature. There is also a sense that even John’s good deeds, such as providing Mare with Frank’s alibi from the night of Erin’s murder, are done with ulterior motives.

John Suggests Going To The Cabin & He Brings A Gun

In the penultimate episode, Billy tells John he’s ready to confess. Then it’s John who suggests going up to the cabin first, likely because he senses Billy’s hesitation and wants to make sure things go the way he has planned. This is yet another example of John’s need to control the situation. When Billy finds a handgun in the toolbox, it’s unclear who packed it. Billy’s reaction to seeing the gun in that scene could be interpreted in two ways. Either he packed it and is nervous John will find it, or John secretly packed the gun, and Billy is surprised when he finds it in the toolbox. Watching closely, Billy appears to be casually placing some extra supplies in the toolbox and is genuinely taken aback when he spots the gun, instantly pausing and looking around. At that moment, Billy’s behavior seems to suggest shock and confusion, indicating that John is the one who secretly packed the gun.

Watching the two men’s behavior as they drive to the cabin in the final moments of Mare of Easttown episode 6 is also telling. John is attempting to play it cool, but his desperation is difficult to mask. He looks like a man in the midst of contemplating an impossible choice. It’s been shown from his previous behavior that he’s clearly trying to keep his family from completely falling apart. If he believes that Billy is less than sincere about taking the fall for Erin’s murder, John may have other plans for his brother. Otherwise, why would he bring a gun to the cabin? John is either determined to keep Lori from ever finding out that he is Dj’s real father and Erin’s killer, or he’s desperate to protect someone else. It could be that John is the one who killed Erin and had Billy help him clean up the crime scene. It’s also possible that they are both protecting someone else, Ryan Ross.

John’s Son, Ryan Ross Knows What Really Happened To Erin

A second possibility is that Ryan found out about his father and Erin’s affair — or caught them in the act — and something happened in the chaos of that moment that caused Erin’s death, either on purpose or by accident. It’s possible that this secret will be Mare of Easttown‘s final reveal. If this is the case, John’s affair ultimately causes Erin’s death, but he may not have been the one to actually pull the trigger. If Ryan killed Erin, this would make Billy’s willingness to confess more believable. He’s not taking the fall for his brother’s mistakes — he’s protecting his young nephew. If Ryan’s involvement in the crime is the true secret John and his son are hiding from Lori, this would also help to explain John’s obvious desperation at this point in the story. He may be worried that Lori will find out about him and Erin, but he’s also distraught over what might happen to his son.

The Photo Jess Gave To Police Reveals The Real Killer

Either way, it seems likely that the photo Jess gave to the police in HBO-Max’s Mare of Easttown penultimate episode will provide the evidence needed to uncover the true identity of both DJ’s father and Erin’s killer. After seeing the photo, the chief is in a hurry to get Mare on the phone. This suggests that there is something in the photo that changes the story and that it likely disproves Mare’s theory that Billy Ross is the killer. Of course, it should be noted that this theory discounts Dylan’s behavior in the last few episodes, which also makes him look guilty. If the Rosses are truly behind Erin’s death, that doesn’t explain Dylan’s disappearance the night of her murder or why he later threatened to kill Jess. If Dylan is a red herring there would need to be some other explanation for this behavior as he’s clearly hiding something. Fans will have to wait for the Mare of Easttownseason 1 finale to find out for sure.

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