Fallen (1998), directed by Gregory Hoblit.
After attending the execution of a scary serial killer he caught, a homicide detective slowly comes to believe the awful truth: that an ancient demon is passing from body to body. It's mission: pain and murder, particularly the intricate persecution of our hero.
In some ways this is a modest supernatural thriller, but I am quite fond of it because it represents a rare horror genre: the sad, autumnal quality of evil. In a lot of popular entertainment evil is interesting, seductive, "Their Satanic Majesties". It is more unusual to show evil as sad, the product of broken, limited beings.
This film and the Millennium (1996) TV series with Lance Henriksen are the most prominent examples I can recall.
It helps that the cast includes actors we tend to love:
Denzel Washington is our hard-working detective.
John Goodman: his partner.
Donald Sutherland: the homicide lieutenant, warning our hero off of the investigation.
Embeth Davidtz: daughter of a detective who committed suicide decades earlier, now a theologian becoming terrified of her subject.
James Gandolfini: a not bright, hostile policeman.
Elias Koteas: the first killer, executed but possessed by an undying spirit.
Notes:
I love the community of cops here, their lack of hand-wringing and the way they take the homicide scenes so calmly. They flip attitude up and down the line and don't have much respect for authority.
In a demonic possession story people are not responsible for their crimes. They don't even remember them. The Devil made me do it.
The film uses a trick beginning and ending, which though clever, perhaps lowers its serious tone. I think it makes the middle narration a cheat.
Available on Blu-ray.