Kalifornia (1993)

Brian Kessler, a journalist researching serial killers, sets out with his photographer girlfriend Carrie on a cross-country tour of the sites of the killings. Sharing the ride and their expenses are Early Grayce--a paroled white-trash criminal--and his girlfriend Adele. As the trip progresses, Early appears more and more unstable, and Brian and Carrie fear that they have a real-life killer in the back seat of their car.