Wesson mixed ruthlessness with indoctrination. His Bible studies and prayer sessions would last for hours. His children told ABC News that they didn't realize they were living in a hellish situation because they were born into it and had no outside influences to teach them otherwise.
The roots of Wesson's obsessions snaked back four decades to the day he staged a homemade wedding ceremony. The bride, Elizabeth Wesson, was just 8 years old.
Elizabeth Wesson told ABC News that she believed Marcus Wesson when he said the Lord chose her to be his wife. She reveled in the attention he showered upon her.
"He said that I belonged to him -- that I was his wife already," Elizabeth Wesson said.
By 14, Elizabeth Wesson was pregnant, and by 26 she had given birth eleven times.
Over the years, Marcus Wesson collected bizarre beliefs and welded them together to create his own vision, which he imposed upon his growing family. He wrote his own version of the Bible, in which he claimed that Jesus was a vampire. He told his family "the end was near."
For years, he warned his wife and children to prepare for the day when the devil with a badge and a blue uniform would show up at their door. Until then, he sequestered and home-schooled the family in a series of hideaways along the California coast. One of the places was Tomales Bay, south of San Francisco, where he anchored a rusted-out sailboat and hid the children.
Gypsy Wesson, 26, told ABC News that Marcus Wesson would leave the children unattended on the boat for four or five months at a time below deck so no one would see them and ask why they weren't in school.
"It felt like being in a prison," Gypsy Wesson told Schadler. "Very depressing -- like, hopeless. And you felt trapped ... nowhere to go."
Two hours south of Tomales Bay was another hideout, in a remote spot high in the Santa Cruz mountains. Wesson had the family pitch a huge army surplus tent and they lived in the squalid camp for the better part of 12 years, away from the prying eyes of neighbors, social workers and police.
For the boys, Bible studies were enforced with whips and sticks. For the girls, Wesson was teaching them a different kind of lesson: something he called "loving."
Gypsy Wesson and Kiani Wesson told ABC News that their father started touching them sexually when they were seven or eight years old.
Gypsy Wesson said she felt it was wrong, but Kiani Wesson didn't know otherwise.
"I didn't know anything else and I thought it was all right," said Kiani Wesson, 33.
When asked why their mother didn't stop the abuse, Kiani Wesson said that she felt her mother was powerless.
"She'd been with my dad since she was eight years old," said Kiani Wesson. "So I felt that she was pretty much, you know, caught up in the same thing."
Psychiatrist Edward Hallowell, director of the Hallowell Centers in New York and Boston, watched "Primetime's" interviews with the Wesson children and said Wesson used fear as a manipulative tool.
"What he basically did was create this crucible of fear," said Hallowell. "He used fear, extreme fear, to get these kids to act completely counter to their self-interest."
As the kids grew older, they were allowed to get jobs as long as they turned all their money over to their father.