Watch TV Series Trial 4 Netflix Online at Couchtuner. Trial 4 is an upcoming eight-part documentary series that tells the story of Sean K. Ellis, who has spent 22 years in prison after being wrongfully convicted at age 19 of the 1993 murder of Boston police detective John Mulligan. Three trials later — two with hung juries and one that got him freed from jail on bail in 2015 — Ellis is facing a fourth trial that will decide whether he will be put back behind bars.