This article contains major spoilers for Mare of Easttown up through Episode 5, “Illusions.” You can also read our interview with series creator Brad Ingelsby and director Craig Zobel about that intense episode, as well as our official review of the HBO limited series.The first episode of the HBO limited series Mare of Easttown ended with a gruesome image: a naked woman with a bullet hole above her eye, dead in a river basin. Murder! By the shocking end of Episode 5, we still don’t know who killed her, and figuring out who might have done the crime is still harder than nailing that vowel-flattening Delaware County dialect Detective Mare Sheehan (Kate Winslet) talks in.

That’s not to say there aren’t plenty of viable candidates as the limited series heads into its final two episodes. It helps that we know so much about Erin, introduced in the premiere as a loving single teen mother of infant DJ and a notably antagonistic ex-boyfriend Dylan (Jack Mulhern), with whom she shared custody of their son. Erin’s home life wasn’t great either: She lived with Kenny (Patrick Murney), her downtrodden widowed father with a significant temper and drinking issues. After a party at which she is beaten down by Dylan’s new girlfriend, Brianna (Mackenzie Lansing), she stumbles off, bloodied and dazed. In the morning, she turns up dead.

Subsequent episodes of Mare of Easttown dig further into her Erin’s past while juggling an investigation into two missing-girl cases that were initially thought might be connected but are revealed not to be in Episode 5. With only two episodes to go, and with Mare reeling from the death of her puppy-dog partner Detective Colin Zabel (Evan Peters), the mystery series will now refocus on Erin’s murder and all the people who potentially killed her. Let’s investigate further, and parse the viable killers and the likely red herrings in order from prime suspects to the technically still possible.

Billy Ross (Robbie Tann) 

Currently, the two Ross siblings, who are the cousins of Erin’s dad, Kenny McMenamin, are the most suspicious characters in all of Easttown, with Billy marginally edging out his brother, John, as the prime suspect. In episode 5, Mare, Lori, and the Ross brothers are watching a Penn State game when Billy reveals that Erin actually stayed with him for a short period of time when things were bad with Kenny following her mother’s death, and it seems to have occurred at a time when DJ might have been conceived. The camera fixates on Mare as this info nugget is divulged and she pointedly asks questions that indicate her thoughts: Could Billy possibly be the father of her child? That would certainly give him motive to murder.

John Ross (Joe Tippett) 

What if it’s not actually Billy and it’s in fact his brother John? Vanity Fair‘s Joanna Robinson has laid out a very convincing theory that John is the obvious killer. We know something is up with John, specifically that he’s once again cheating on his wife, Lori, and telling his son Ryan (Cameron Mann) to keep quiet about his infidelity. With whom is this affair? We don’t know-Frank’s fiancée, Faye, perhaps?-but apparently there’s one woman who has recurred in his life, at least based on what Lori asks Ryan. Whatever he is, he is certainly not an honest person, one that his driving his own child into anger and sorrow.

Deacon Mark Burton (James McArdle)

Deacon Mark Burton is very suspicious-in a way we’re suspicious of as television viewers. He almost seems too likely. Not only was he accused of rape at his previous parish, he saw Erin the night of her murder. According to his story, he picked her up and drove her to Brandywine Park. That’s why he had her bike in his car, which he later disposed of when the investigation started. If Burton didn’t kill her, he at least knows crucial evidence about what happened to her that night.

Dylan Hinchey (Jack Mulhern)

Dylan, who turns out is not the father of Erin’s baby, has only grown more suspicious as time has gone on, and he started out pretty suspicious. Not only did he stand by idly while his new girlfriend, Brianna, spits accusations and throws punches at Erin, his attitude toward his ex comes off as straight-up insidious. He even refuses to help pay for DJ’s much-needed ear surgery back when he thought he was the father! He gets even more suspicious in episode 5 when Brianna reveals that when she woke up the night of the murder he wasn’t anywhere to be found, and then he goes on a little book burning expedition, throwing all of Erin’s diaries into a fire. What’s he hiding? Still, for a show as densely plotted as Mare of Easttown, having the ex be the murderer would be too easy without some sort of misdirection, so we’re going to say… it’s probably not him?

Richard Ryan (Guy Pearce)

What is the deal with Richard Ryan, a creepy serial killer name if we’ve ever heard one? He’s the only outsider in the premiere episode, which makes him a suspect by default. Mare meets him at the bar, where he explains that he’s the author of a successful book and that he moved to the Philadelphia area two months back from Syracuse to guest-lecture at a local college. They hit it off and end up sleeping together, so maybe he’s going to serve as a plot device to shake up Mare’s life. He was with Mare that night, an alibi as sturdy as they come. But what happened after Mare went home? Also Guy Pearce is one of the most famous people on the show. Is this really all he’s going to do?

Frank Sheehan (David Denman)

Mare’s ex-husband, Frank, held his engagement party the night Erin died, and most of his and Mare’s family members and friends were in attendance, so he would seem to have a solid alibi. However, the party had broken up by the time Erin walked into the woods, which we know because Siobhan went to the woods gathering after her dad’s engagement party, and Frank himself showed up at the bar where Mare was drinking after the high-school basketball ceremony. So he could have snuck away conceivably. But what’s the motive? Despite Mare’s suspicions that her old husband was the father of Erin’s baby, that was disproven by a DNA test. So Pam’s ex from The Office is almost certainly not the killer, but one of his and Mare’s friends or relatives, though, could be, and Frank may know more than he’s letting on..

Siobhan Sheehan (Angourie Rice)

Could this crime hit close to home? Mare’s daughter tried to help Erin during and after Brianna’s beatdown but she was rebuffed. While she’s one of the last known people to have seen Erin alive, it would be a true twist, and probably not a good one, if she turns out to be a secret killer. Her presence may instead be an indication that the killer or possibly the father of Erin’s baby (wild theory: what about Kevin!?) may be closer to Mare than she suspects.

Kenny McMenamin (Patrick Murney)

Erin’s dad is full of rage, but his anger manifests more as frustration with his lot in life and is largely directed toward Dylan, who he decided to track down and shoot in episode 2. Gunning down another teen certainly implies he has the capability to kill, but targeting Dylan out of sorrow and anger seems to indicate that he didn’t actually kill his daughter. If he did, why would he want another prime suspect dead?

Brianna Delrasso (Mackenzie Lansing)

Despite the hostility toward and actual violence committed against Erin, bad-girl Brianna is a classic murder show red herring. Sure, the ambush assault may have contributed to Erin’s death by sending her on a path that ultimately leads to an untimely death, but Brianna’s behavior comes across as childish, not murderous. Plus, it would just be head-slappingly stupid if the killer turned out to be the openly hostile new girlfriend who’s jealous of the ex.

Ryan Ross (Cameron Mann) 

John and Lori’s son is clearly going through it. He wails on a lunchroom bully who flings food at his sister, and breaks down following the incident as his mother asks him if his father is “doing it again.” It seems very unlikely that a killed Erin, but he has been trained to protect his dad, and if his dad was somehow implicated in Erin’s life, perhaps he cracked, left home in the middle of the night, and somehow got to a park where he found a gun and shot Erin and made it home without anyone noticing. Still, he almost certainly knows more than he’s told Lori so far.

Lori Ross (Julianne Nicholson) 

OK, hear me out: Maybe it’s Lori, Mare’s best friend, trying to keep her family together if the Rosses are involved in some way. This cockamamie theory is probably unlikely, but what if Lori found out something was awry with her husband and her brother and took matters into her own hands? It would be a somewhat ridiculous ending, but it would hit Mare very hard.Want more Thrillist? Follow us on Instagram, Twitter, Pinterest, YouTube, TikTok, and Snapchat.

Esther Zuckerman is a senior entertainment writer at Thrillist. Follow her on Twitter @ezwrites.