What more is to be said about the Zodiac Killer? The serial murderer who terrorized the Bay Area in the late 1960s has been the subject of numerous films, books and TV shows.

And now an upcoming documentary series on FX is promising fresh information connected to the legendary cold case.

“Oh, yeah, we definitely found stuff out that nobody knew,” says Ross Dinerstein, executive producer of “The Most Dangerous Animal of All.” “ … We connected some dots that people never connected before. A lot of new stuff will be revealed.”

“The Most Dangerous Animal of All” is a four-part series based on the 2014 book by Gary Stewart. It explores Stewart’s obsessive search for the biological parents who abandoned him as a child and how he came to believe that his father — Earl Van Best — was the Zodiac Killer. The series debuts on FX and Hulu in March.

Dinerstein and director Kief Davidson appeared in a panel discussion at the Television Critics Association press tour to promote their documentary. To avoid spoilers, the filmmakers didn’t go into details. But they revealed that much of their new information is connected to how investigators handled — or mishandled — the case.

“Part of the reason why the Zodiac case was not solved was due to a lead detective’s obsession,” Davidson said. “I can’t reveal too much more because, actually, there’s an element in the Zodiac case that’s really not been talked about before that we uncovered and got people to talk about how that explains why it wasn’t solved in the 1970s.”

Davidson went went on to say that there existed a “culture within the (San Francisco) police department that you don’t talk, you don’t rat out your fellow officers. I wouldn’t go as far to say that there was a cover up, per se, but there is certainly information that these former detectives were not talking about that I ultimately did get them to talk about.”

Davidson, who says he isn’t a true-crime buff, says he prepared for the project by immersing himself in previous Zodiac-related documentaries and came away unimpressed.

“I found that, by and large, they were all very sensational, rehashing stories that have just been told over and over and over again,” he said. “They just didn’t do their own deep dive. They didn’t do the work.”