Sergeant Ellis is a non-canonical character, created for the 2022 miniseries Why Didn't They Ask Evans?, an adaptation of the Agatha Christie novel of the same name. He is a member of the Marchbolt police force and the only policeman seen in the adaptation. He does not have a particularly active role in the investigation.
He comes to the church to alert the Reverend of a string of bicycle robberies in the neighbourhood, discouraging Mr Angel from further abusing the Reverend. He also looks into the death of Dr Thomas but does not believe Bobby's claim about it not being a suicide. At the end of the story, he is oblivious to Mrs Roberts's cries for help through the window as Bobby is trying to tackle Roger Bassington-ffrench, but he comes in just in time to see Mrs Roberts knock Bassigton-ffrench unconscious with a vase.