Three documentaries from director Errol Morris. 'The Thin Blue Line' (1988) uses drama and documentary techniques to explore the murder of a police officer in Dallas in 1976, and the trial and conviction of his kiler. But Morris concludes that the man convicted for the crime may not have actually pulled the trigger in the shooting. 'Vernon Florida' (1981) takes a fly on the wall look at an eccentric small American town. Finally, 'Gates of Heaven' (1980) looks at the emotional turmoil when a local pet cemetery is forced to close its gates, and the bodies of the animals have to be transferred to another one.