'The Truth About Jim': Sierra Barter Talks Grandfather and Possible Zodiac Killer Connection (EXCLUSIVE)

The Truth About Jim opens with Sierra Barter revisiting a harrowing memory from her childhood. She was 7 years old and walking through the woods with her grandmother. Barter recalls feeling scared but not knowing why until she realized her grandmother was the one who was really living in fear. "Because she was married to a monster," cries Barter. "His name was Jim Mordecai, and he was a very bad man."

The four-part Max docuseries takes us through the ways in which Mordecai physically and emotionally tortured those around him. While searching for other victims whose lives he might have ruined, Barter makes some disturbing connections between Mordecai and two infamous crime sprees. "Was he a killer?" she asks herself. Sierra Barter's grandfather certainly had something dark inside of him.

Anyone who didn't know Mordecai well would describe him as a nice guy with a good physique. He was a science teacher who also dabbled in landscaping but his real passion appeared to be "inciting fear," said his stepson Michael Probst. Probst recalled two instances from his childhood that summed up who his stepfather was. One was when Mordecai encouraged his pacifist stepson to fight a bully, taunting him when he didn't want to. The other was taking him for a drive and showing him where a dead body was found.

Mordecai's third wife Judy, Barter's grandmother, said he "seemed kind of wholesome" when they met at her daughter Shannon's school. Her previous marriage had ended in divorce, leaving Judy with very little self-esteem. How could she have predicted that he would eventually be so frightening, that Judy would sleep with a gun? His reputation among some students at school was that he was a cool teacher. Mordecai would let kids drink at his home and would hang out with them in his hot tub.

In the series, Shannon talked about how he would harass her at school. "He got off on that. It excited him," she said. One day Mordecai cornered Shannon in the green house at the school where he threatened her. Things only got worse when he married her mother. When Barter spoke to her family about Mordecai, each conversation was more chilling than the last. The most upsetting story was from Christi Probst, his stepdaughter from a previous marriage, who alleged he repeatedly raped her throughout her childhood.

As Barter dug deeper, she encountered other former students from the high school where Mordecai worked who had similar tragic experiences with him. Many of his victims were part of the Future Farmers of America club which was led by Mordecai. His modus operandi was isolating young girls in the club, then preying on them using their interests. Is it possible that Mordecai didn't stop at assault?

The bulk of the docuseries centers around Barter's theory that her grandfather was involved in a series of unsolved murders from 1972 to 1973. All of the victims were hitchhikers in Sonoma County; most of them were tied up or assaulted, and left on the side of the road. Authorities referred to these crimes as the Santa Rosa Hitchhiker Murders. Some fit Mordecai's M.O. and he certainly lived in the area at the time. He also drove around with a large knife and often threatened to hogtie and kill women which is what happened to some of the Santa Rosa victims.

While digging into that theory, Barter was momentarily sidetracked by another hypothesis. A few years before the Santa Rosa murders, another crime spree had gripped the same area. A string of seemingly random murders were traced back to one person who called himself the Zodiac. The timeline matched up, though the Zodiac's crimes never involved sexual assault. Still, Barter had to eliminate this possibility.

She spoke with Zodiac expert Mike Butterfield who put Barter at ease when he said the Santa Rosa murders didn't look like the work of the Zodiac. And furthermore, there wasn't enough to attach Mordecai to the Zodiac.

Distractify spoke with Barter about that reveal which she said made her feel better. Prior to that moment, she was afraid things had gone "too far" and found herself wondering if she would "ever be the same again."

Regarding her grandfather, who passed away in 2008, we asked Barter if she wished he was still alive to answer for his sins. "The good but terrible part is, my mom was always super vocal with him," explained Barter. "She never let him believe that she thought he was a good guy." Barter thinks he had controlled the narrative for too long. "I don't know if I would have anything to say to him," she said. "I think I'm super thankful he's gone."