She said she killed her son and hid him in a manure pile. The truth is more sinister, police say

Stephanie Jackson, Deborah Sue Rudibaugh and David Jackson. Photo / Gunnison County Sheriff's Office

It was all about the land.

The 7 11 Ranch stretches over 700 empty acres on the wind-tossed western slopes of Colorado's Rocky Mountains. The closest town - Gunnison - is a 20-minute drive. China blue skies cap swinging fields of grass. Foothills climb the horizon. Horse trails rope around the hulking boulder outcroppings. Rainbow and cutthroat trout nose up Quartz Creek. Six cabins are clustered on the property, arranged around the main house, a log structure hung with animal skulls and antlers.

Inside that house, in the early hours of May 16, 2015, Deborah Sue Rudibaugh slipped into her son's bedroom. She held a stainless steel Smith & Wesson "Lady Smith" .357 caliber revolver. As she would tell police more than two years later, that night she shot and killed her son Jacob Millison while he slept. "I was afraid he was going to kill me," she told investigators, according to an arrest affidavit obtained by the Denver Post.

She said she had acted alone, moving the body herself into a pile of horse manure. Later, fearing wildlife would get to the corpse, she relocated her son. Last July, after Rudibaugh confessed, police found Millison - he was in a pit, lying among severed sheep's heads, the Denver Post reported.

Rudibaugh's confession last summer might have solved the mystery of the 29-year-old's abrupt disappearance. But investigators had reason to think Rudibaugh was lying.

When he died, Millison was vigorous and fit, his 170-pound physique strong from Brazilian jujitsu. His mother was tiny, just 5 feet tall and 70 pounds, the Denver Post reported. Only a week before the shooting, Rudibaugh had undergone gallbladder surgery. Could this small woman in her 60s haul her son's body around the ranch, police wondered?

"Just because somebody confesses, you have to continue to investigate to corroborate that," Gunnison County Undersheriff Mark Mykol recently told the Gunnison Times.

This week, authorities have released a fuller, and more sinister, account of Millison's death. On March 2, Rudibaugh was arrested and charged with first-degree murder. But Stephanie Jackson, Rudibaugh's 33-year-old daughter and Millison's sister, was also arrested in the crime. So was Jackson's husband, David Jackson.

Court documents paint a bizarre family drama, filled with twists, including a contested will, violent threats, incriminating Facebook posts and an alleged plot among family members targeting Jacob Millison.

Investigators believe the control of the ranch - valued at $3 million - is what led family members to turn on Millison.

The arrests come as a vindication for Millison's friends, who have repeatedly pressed investigators to look at the 7 11 Ranch's residents for the key to their friend's disappearance. "Literally days before he went missing he told us if anything ever happened to him, it was his family," Randy Martinez, Millison's friend, told CBS Denver this week.

Court records indicate that none of the defendants have entered pleas in the case. Lawyers are not listed for the defendants.

Jackson was a year older than her brother. The two never got along well, Rudibaugh told the Gunnison Times in June. When Jackson was 7 and Millison 6, their mother split with their father, Ray Millison. She later married a Colorado rancher named Rudy Rudibaugh. The two children and their mother moved to the 7 11 Ranch, four hours by car from Denver.

Rudy died in 2009, leaving the valuable property to his widow. Her own will stipulated that the 7 11 would go to Stephanie Jackson, Jacob Millison, and one of Rudy's children from his first marriage. In 2012, Jackson and her husband moved out of their house in Denver and relocated to the ranch. There, Stephanie Jackson led "horseback rides out of the ranch," according to a community newspaper.

On May 15, 2015, Millison and a friend went to see "Mad Max: Fury Road." After that, he stopped answering his phone.

"We had plans on that next day," Randy Martinez told CBS Denver. "He wouldn't just disappear for no reason."

When friends asked Rudibaugh about her son, she had an explanation. "She told us the story that he was on a trip with the MMA gym," Martinez said. "I know a bunch of the guys in the MMA gym. So we called all of them, and were like, 'Is Jake with you guys?' They were like, 'No, we were in Denver.' "

Rudibaugh continued to say her son had left on his own. In August 2015, she finally filed a missing person's report with local law enforcement. She told police her son was using drugs - steroids, cocaine and mushrooms - and hanging with a dangerous crowd, The Washington Post has reported. Rudibaugh also told police her son had stolen one of her books, titled "How to Disappear Without Leaving a Trace."

The mother added that after Millison left, she tore up her will, creating a new document leaving the ranch only to Stephanie Jackson.

Millison's friends didn't believe her explanations. It did not sound like Millison. He was a meticulous planner, and would never leave for a trip on a whim. He also had left behind two prized possession - his dog, Elmo, and his Harley-Davidson motorcycle. The friends started a Facebook page - Where is Jake Millison - to bring more attention to the disappearance.

Police continued to search for two years.

Eventually, in July 2017, they received a tip - about what, law enforcement still has not said. But 60 officers and five cadaver dogs arrived at the 7 11 with a search warrant.

Rifling through the lodge, they hit on a significant clue. Inside a file cabinet, investigators found a will leaving the ranch to Jackson only. It was not, as she had told police, dated after Millison vanished. It was dated April 27, 2015 - weeks before Millison disappeared.

The mother came up with a different explanation. She had changed the will in April. It enraged Millison. Her son physically and verbally abused and threatened her, telling investigators he used her like a "crash test dummy with his mixed martial arts thing," according to the Gunnison Times. "He would hold me and sit on me and stuff."

Rudibaugh told investigators she feared for her life, shooting Millison in his sleep before he could kill her. She acted alone, she claimed. Her daughter and son-in-law were in Denver that night.

But again: How could a frail woman in her 60s move the body?

A Facebook message turned law enforcement toward Stephanie Jackson.

On the morning after Rudibaugh had said she killed her son, Jackson posted on Facebook: "Have you ever been woken up with such awesome news you wanted to run outside screaming?" according to The Post. In addition, police learned David Jackson had been seen driving the victim's Harley-Davidson. Court records showed Millison had filed for a restraining order in January 2013 against his brother-in-law after a fight.

And when police checked cellphone data, it showed the Jacksons were in Gunnison - not Denver - when Millison was killed.

In a January 2018 interview with police, David Jackson allegedly implicated his wife.

"Honestly after this and all of that, I have a strong feeling it could have been Steph," David Jackson said, according to court records. "I really get a hunch it was Steph, but I'm not positive."

The couple later allegedly failed a polygraph test about their involvement and knowledge of the killing.

"Stephanie knew that Deborah's will had been changed to make her the sole heir of the ranch," this week's arrest affidavit stated. "Stephanie's lies and actions after the murder show that she knew Jacob was dead immediately . . . and intended to cover up the homicide."