Boston Detective John Mulligan was working a night shift in a Walgreen’s parking lot in 1993. An employee was walking past Mulligan’s car when he saw something horrific (the employee speaks in “Trial 4” about the trauma he still carries): the officer had been shot multiple times, mostly in the face. It was no mere robbery. It looked brutal and personal. And the officer’s gun was missing. Rumors started quickly that Mulligan’s pants were found around his ankles and that the murder looked more like an execution than a mere gun robbery. However, another murder investigation across town revealed that a teen named Sean Ellis had been in that Walgreen’s around the time of the murder with his buddy Terry Patterson. While they had no motive other than to steal a gun, Ellis and Patterson were arrested and tried. The first two trials led to deadlocked juries; the third convicted Ellis of a crime he clearly didn’t commit. “Trial 4” is about the fight for that fourth and final trial, which took over two decades.
“Trial 4” is one of the densest true crime docuseries ever made. There’s archival footage of the case, including a cop arriving on the scene, and multiple interviews with major players on both sides—although it’s telling that every episode ends with a list of who was contacted but refused to discuss the case to make sure to remind viewers of the efforts to get both sides of this story. The series focuses most of its energy on Ellis himself, following him around as he awaits trial for what everyone hopes is a final time, and works with an unforgettable attorney named Rosemary Scapicchio, who is the kind of person every wrongly convicted soul wants on their side, fearless and aggressive in her efforts to prove Sean’s innocence.
A cover-up of corruption is revealed throughout “Trial 4.” The investigating officers in the Ellis case were undeniably corrupt, investigated multiple times in the city of Boston for stealing money from people they arrested—a young man tells a story of being tied to a chair in his own apartment while they basically robbed him—and there’s significant evidence that those officers had a connection to Mulligan that needed to stay secret. Putting Ellis away meant that the corrupt network would go away too. These people paid witnesses, robbed criminals, and coerced testimony, and “Trial 4” devotes a lot of time to analyzing the entire system that allowed them to get away with it.