The Glatzel family shares their experiences with demonic possession in Netflix’s The Devil on Trial, but the documentary omits some details from the true story. The Devil on Trial tells the tale of David Glatzel, who was allegedly possessed by a demon when he was 11 years old. The situation only became more tragic for the Glatzel family when the demon that possessed David took an interest in David's brother-in-law, Arne Johnson, which Johnson claims led him to commit murder. David’s possession became famous both for the involvement of Ed and Lorraine Warren, as well as Johnson’s assertion that “the devil made [him] do it” at his murder trial.

https://screenrant.com/devil-on-trial-david-glatzel-biggest-details-missing/