This summer marks 40 years since serial killer David Berkowitz — who was known as “Son of Sam” — terrorized NYC and went on a killing spree that claimed the lives of six people. A new generation is learning about the horrific killer, who remains in prison to this day, thanks to Investigation Discovery’s two-hour special Son of Sam: The Hunt For a Killer, which premieres tonight at 9 p.m.

As he continues to serve his life sentence, many have wondered how police were able to nab to the ruthless killer, who had New Yorkers living in fear for their lives for more than a year. And as hard as it is to believe, it came down to a simple parking ticket to finally catch the horrific criminal.

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Berkowitz was arrested in Yonkers on Aug. 10, 1977 after a woman named Cacilia Davis called police to report suspicious activity. She was walking her dog late at night in her native Brooklyn when she saw a police officer ticket a car nearby. A man later approached her, and seemed to be observing her and waving a “dark object” before getting into the nearby ticketed car. She ran home, and shortly thereafter heard gunshots — it was later revealed that what she heard was the murder of Berkowitz’s final victims.

Days after the shooting, Davis called police to report the unnerving incident, and they checked their records of all the cars ticketed that night. This led them to Berkowitz, as his Ford Galaxie was ticketed for parking near a hydrant.

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The local cops in Yonkers suspected Berkowitz — who was known to the authorities for his erratic behavior — because he mentioned local crimes in his horrific “Son of Sam” letters left near the victims’ bodies. After obtaining a search warrant for his home and vehicle, cops came across the weapon used to commit many of the murders — and a day after his arrest, Berkowitz confessed to the crimes, claiming that his neighbor Sam Carr’s dog, Harvey, was possessed and ordered him to kill (hence "Son of Sam").

After pleading guilty to all of his crimes, on June 12, 1978, he was sentenced to 25-years-to-life for each murder, to be served consecutively. He has since become a born-again Christian while behind bars in upstate New York, and has expressed no interest in receiving parole, though he was first eligible in 2002. He said, “In all honesty, I believe that I deserve to be in prison for the rest of my life. I have, with God’s help, long ago come to terms with my situation and I have accepted my punishment.”