Zodiac

The Zodiac Killer was probably one of the most notorious US serial killers of the 70s, mainly for his habit of sending cryptic coded messages with threats of further atrocities and demands that they be printed on the front page of the San Francisco Chronicle. This case has been the basis of several movies, both documentaries and fictionalised accounts, and David Fincher's take is a good one.

The film opens with a brutal murder, followed by the first of the coded messages that catches the eye of Robert Graysmith, political cartoonist on the Chronicle. It starts an obsession with the case that persists for years, as well as showing the effects that it has on the detectives in charge of the investigation. Fincher's direction is stylish, with good use of music to set the scene in the early 70s. There are a couple of distracting CGI shots of San Francisco of the period that haven't held up particularly well, but on the whole it's a good crime thriller. 

The film does develop a convincing theory for the identity of the killer, but as is well known the truth is still ambiguous even to this day. My money's on Ted Cruz.