David Berkowitz, the so-called Son of Sam, has been imprisoned for decades following a string of brutal shootings in New York in the late seventies. He initially claimed that a dog named Sam commanded him to murder, but years later walked that back, saying he had actually been part of a satanic organization known as “the Children” who conspired with him in the murders.

If it sounded outlandish, it was no more or less so than that Berkowitz had served at the pleasure of a homicidal dog. But his change of story fascinated Maury Terry, an investigative journalist who spent a great deal of time and effort trying to piece together this most unusual puzzle.

Documentary filmmaker Joshua Zeman (“Murder Mountain”; featured image) has been working, in one form or another, on the new docuseries “The Sons of Sam: A Descent Into Darkness” for the better part of a decade. He initially met with Terry, sensing that an investigation into the decades-old case had the potential to draw in a great deal of viewers.

“He was both a kind of mentor and ‘unreliable narrator’ all in one. He was definitely conspiratorial,” Zeman told me about meeting with Terry years ago. “But at the same time, looking at his evidence and comparing it with other police officers, some of it really made sense.”

Zeman said he had also come upon the case in an odd way thanks to his 2009 film “Cropsey,” which researched a New York boogeyman of the same name. That film led him to the very real child kidnapper Andre Rand, who claimed connections to the Children—and Berkowitz.

“Not only was it connected, but there was the idea that Berkowitz didn’t act alone, and he was part of a cult,” Zeman said. “I of course didn’t believe any of it…until a number of NYPD detectives sat me down and said, ‘Let me tell you a story.’”

The detectives suggested a book called “The Ultimate Evil,” whose author was none other than Maury Terry. Zeman, a New Yorker himself, admits the book “scared the hell out of me,” especially as someone typically drawn to debunking conspiracies and urban legends.

His initial plan was to adapt “The Ultimate Evil” as a drama, especially as he was less than credulous as to Terry’s theories. However, after speaking with Terry several times at his Yonkers apartment, Zeman began to see the value of revisiting the “accepted” version of events involving the Son of Sam murders.

“It was a fascinating case that this one armchair detective could [challenge] what the whole world believed,” Zeman said of Terry’s exploits, adding that Terry’s quest sent him down “a rabbit hole.” “As somebody who has spent his career telling true crime stories, I found that super fascinating. It was almost like my own cautionary tale” of not going too far deep after the White Rabbit himself.

However, Zeman’s docuseries does indeed follow Terry’s obsession down said rabbit hole. In addition to vintage footage from the late seventies through the early nineties, “Sons of Sam” interviews Terry’s friends, family members, retired police officers and Terry’s contemporary journalists. Some of them praise his quixotic quest, others claim he was nuts. All seem fascinated by this unique man who was a combination sleuth and conspiracy theorist in the ages before Twitter.

Zeman believes that people respond to true-crime docudramas because of our innate wish to try and solve a puzzle—even when there seems to be no end result and no idea what the picture is even supposed to look like. There’s no drama to knowing the ending in advance, he said, and there’s also a perverse draw to serial killers and macabre unsolved mysteries.

“We like to go into the darkness. Because that allows us to come home and play with our kids,” Zeman said of leaving the horrific behind when the credits roll. “It allows us to be able to exist in the light when we spend some time in the dark.”

Furthermore, audiences get to play amateur detective at home, and compare their theories with family and friends as to who is “right.” This is similar to how audiences at the beginning of pandemic last spring—back when at-home viewing became the norm and not the exception—argued over whether or not Carole Baskin had in fact fed her late husband to her large pets in “Tiger King.”

“I actually think those are the best [stories] because then we all get to play the game. We all get to be Sherlock Holmes,” Zeman said. “My version can be right, your version can be right, our friend’s version can be right. That allows us all to win the same game.”

Zeman and his team had filmed many of Terry’s files and notes—and flowcharts linking Berkowitz to seemingly every other conspiracy theory out there—last year before the pandemic set in. Zeman would have liked more time to photograph even more of Terry’s archives, but he had to edit the four episodes of “Sons of Sam” with what he already had.

“When Maury found out this original information, he was called a crackpot by the NYPD. And unfortunately that made Maury Terry double down,” Zeman said, adding that such zealotry led Terry away from “legitimate” news outlets and into the open arms of the tabloid press, “which only undermined more of his credibility, which led him to be even more crazy.”

“In some ways Maury Terry made a deal with the devil by taking that story to the tabloid press,” Zeman said. “[Figures like] Morton Downey Jr. and Richard Bay were the only people who would listen.”

To add a bit of drama to his docuseries, Terry’s writings are given voice in the series by Academy Award-nominated actor Paul Giamatti, who credibly lends Terry’s writings the requisite amount of both gravitas and spectacle.

Even though “Sons of Sam” runs four hours, Zeman said there was so much more he had to leave on the cutting room floor. Accordingly, he also has put together a multi-episode podcast called “Searching for the Son of Sam” that dives even deeper into the case.

“I’ve spoken to over twenty New York Police Department detectives who every time they tried to investigate this case were shut down, and they know in their investigations that Berkowitz didn’t act alone,” Zeman said. “I would say there’s a preponderance of evidence to say that Maury Terry is at least right in asking the questions.”

However, even if Terry might theoretically be proved “right” in the end, the fact is that his obsession ruined his marriage, his health and, to a great many observers, his reputation as a journalist.

Thus, even after Terry’s work, and Zeman’s film, the “truth” of the case may never be completely known. Ergo, Zeman believes that “Sons of Sam” is not only a true crime documentary, but also a cautionary tale about how obsession can destroy even the best-intentioned.

“As a director, and as someone who lives and breathes true crime, it never feels like the end. It’s just the end of ‘this chapter’ of the story,” Zeman said.

He added: “Be careful, because you may not find your way out.”

“The Sons of Sam: A Descent Into Darkness” is now available on Netflix.