Mare of Easttown is a huge hit because of its great mystery and interesting people. This drama grabbed viewers' attention by showing life in a small town in Pennsylvania. The most important question in the show was always: Who killed Erin in Mare of Easttown?
The answer was hidden deep in the town's secrets. Detective Mare Sheehan had to check on her own friends and neighbors to find the person responsible. The final answer was shocking and very upsetting. It turned out the killer was not someone new, but his friend's son, Ryan Ross.
The murder involved a terrible choice made by a teenager.
Mare of Easttown: Investigating Erin's death

What did everyone think happened?
When Erin McMenamin was killed, the police first suspected several people. They looked closely at Frank Sheehan, Mare’s ex-husband. They also looked at Deacon Mark Burton, who did something shady with Erin's bike.
These people had secrets, but they were not the killers. This search was difficult because many people in Mare of Easttown were hiding things. The true killer stayed quiet for a long time.
The real killer’s secret
The murder was finally traced back to the Ross family, who were very close to Mare. John Ross, Mare's friend, confessed first. He claimed he had an affair with Erin and shot her during a fight. This seemed to be the answer.
However, Mare knew that John was lying to protect someone else he loved. He was trying to save a family member. Lori Ross, John's wife and Mare’s best friend, was also covering up the truth. The lies were tearing their family apart inside Mare of Easttown.
Mare finds the true answer
Mare’s good detective work led her to the final answer. She focused on the murder weapon, a special kind of old gun. The gun belonged to a neighbor, Mr. Carroll. Mare discovered that only Ryan Ross, John and Lori’s son, had access to the shed where the gun was kept. Ryan did yard work for Mr. Carroll. Mare found the gun hidden at the Ross house.
This proved the painful truth: The actual killer was Ryan Ross, the teenage son.

Why did Ryan do it?
Ryan's reason was simple: He wanted to protect his family. He knew his father, John, had an affair with Erin. He was afraid that his parents would divorce, as they almost did. Ryan thought that if Erin disappeared, his family would be safe.
Ryan took the gun to the park so that Erin wouldn't leave his family alone. While they were fighting for the gun, Ryan accidentally shot her. He panicked and called his father. John and Billy then tried to make it look like someone else had done it. This desperate act caused so much pain. The answer to who killed Erin in Easttown has destroyed so many lives.
The show is truly about how people handle deep sadness and hurts. After the murder case was finished, Mare started facing her own pain about her son's death. Mare of Easttown proves that one bad event can uncover all the other secret problems hiding in a town.