What started as an inquiry into Hattie Best Polk’s family history helped her orphaned relative discover his father, who might have been the infamous Zodiac Killer.

The story is part of a documentary series that premiers on national television Friday night, chronicling how a man set out to find his biological father, but ends up discovering the unsolved identity of a cryptic serial killer who claimed to have killed 35 people in the 1960s and ‘70s.

“I got involved in this when I got a phone call from someone I didn’t know, but was related to me,” said Polk, a long-time Lake Junaluska resident. “I didn’t think anything would ever come of it.”

Polk said she is the Best family historian, and was referred to by her family members when a stranger named Gary Stewart called years ago, wanting to know more about his birth family, especially his father.

Although Polk said she did not know anything about Stewart’s father, his grandfather was a cousin of her father. From there, Polk taught Stewart the family knowledge of his forefathers.

Stewart attended family reunions, visited the family cemetery, saw their old homeplace of Horry County, South Carolina, and a new family tie was discovered.

“I think that contact was very important,” Polk said. “It was the first time that he had concrete facts about his father’s family and where they lived.”

Stewart endured a decade-long search for his biological father, which, to the family’s surprise, led him to discover the identity of the Zodiac Killer, who was never caught.

In 2018, Stewart called Polk about bringing a film crew to interview her for a documentary about his 2014 book, “The Most Dangerous Animal of All.”

“They came to my house to make pictures and get my story of what I knew about our family,” Polk said. “It’s not every day that a movie company from California comes all the way to Lake Junaluska.”

To watch a four-part docu-series on Stewart’s search, and to see the Haywood County connection to his believed discovery of the Zodiac Killer, tune into the FX channel starting at 8 p.m. Friday, March 6.

“Although it didn’t turn out to be a happy ending for him, it was satisfying,” Polk said. “It set his soul free about who he was, no matter.”

Across the family, opinions vary on the validity of Stewart’s conclusion, but Polk said she has no opinion on either side.

“To come to grips with the truth is therapeutic,” Polk said. “I am proud that Gary pursued this. I feel grateful that the little bit I did helped him to find his roots, because he searched for years and it tore him to pieces.”

Stewart’s story emphasizes the importance of knowing where one comes from, and the significance of writing down the family history, Polk said. Without her memoir on the Best family history, “Out of My Life and Reflections,” many of the details tying Stewart as kin would have been lost.

“It is criminal, I think, not to record your family history for future generations,” Polk said. “It’s a moral obligation to insist that we write these things down.”