Grizzly Man follows the same pattern, except it's not only based on a true story, it's a documentary assembled from footage shot by the madman in question, Timothy Treadwell.
This totally worked, as a nature travelogue, a character study, a murder mystery, a tragedy, and as a grand pronouncement on human nature. One of the great things about it was how Herzog brought his point of view to the material, framing it not only as a director but as a character in the film. No non-commital, Errol Morris-style "objectivity" here. Herzog marvels at the video footage shot by Treadwell, but he clearly considers him a misguided fool. At the same time, he extends him sympathy as a truly troubled soul. At one point he flat out rejects Treadwell's utopian view of the supposed harmony of nature in a memorable voiceover:
Here, I disagree with Treadwell. I believe the common character of the universe is not harmony, but hostility, chaos and murder.This neatly summarize Herzog's entire career, and it sounds even better in his clipped Teutonic accent.
He also turns up some creepy supporting characters, including one of Treadwell's former lovers/employees, and a coroner who starts out in deadpan clinical fashion, but gets more and more worked up describing Treadwell's death and dismemberment until he could have been auditioning for a John Waters movie.