Evil Incarnate

For more than a year, the attacks by the mysterious Son of Sam terrorised all of New York City. A fear like the metropolis had never experienced before gripped the city. All because of an unknown phantom who roamed the streets at night with a .44 calibre revolver, looking for his next victim. No one knew when or where the shooter would strike next. No one was safe from him.
On Wednesday, 10 August 1977, the NYPD arrested a postal worker from Yonkers, David Berkowitz, in connection with the Son of Sam attacks. He subsequently confessed to shooting thirteen people, six of whom did not survive his attack. The case was officially closed.
However, for journalist Maury Terry, something about Berkowitz's confession didn't add up. How was it possible that some of the police sketches of the perpetrator bore no resemblance to him? Why did the testimonies of individual witnesses contradict each other so fundamentally? What was the meaning of the ciphers in the letters he used to taunt the police before his capture? And what role did the mutilated bodies of German Shepherds found near his flat and the satanic cult that met in a nearby park play in all of this?