The former jail mate says the confessions came during a conversation the two had at the Park County Jail.
Kimball denies killing anyone other than the four people whose murders he admitted to in 2009. Kimball is in prison after pleading guilty to second-degree murder in the disappearances of three Colorado women in 2003 and his uncle Terry Kimball in 2004.
9Wants to Know has also learned Kimball referred to 17 murders in forged FBI documents that investigators say he created while in prison.
Kimball is currently the main suspect in the 2004 Westminster murder of Catrina Powell. Powell's naked body was found behind a strip mall. Her hands had been cut off and police believe the killer put acid elsewhere on her body.
"I was not at the Catrina Powell site ever," Kimball told 9Wants to Know in recent phone interviews from prison. "I've never met her. I've never seen her before they showed me a picture of her when they came to the prison to interview me."
Kimball's former jail mate says Kimball told him he picked up a prostitute on Colfax Avenue and killed her. The jail mate says Kimball also admitted to putting acid on the victim to see how it would affect a person's body.
Investigators tell 9Wants to Know those are details only the killer would know. The investigators asked to not be named because they were not given permission to discuss the case publically.
Investigators do not consider the inmate who came forward with the information a suspect in Powell's murder, but declined to say why.
Kimball is a former FBI informant who tricked the FBI into not objecting to his release from prison in 2002 when he convinced them he had information that could help the FBI solve other crimes.
The FBI has declined to speak publically about the latest accusations, but 9Wants to Know has previously confirmed that state and federal authorities believe Kimball may be tied to unsolved murders in the area.
"You can't go around and accuse me of every missing person or every single homicide, I mean that's ridiculous. That's an easy out for investigators," Kimball said.
Kimball says he could not have committed the Powell murder.
"I was out of state when this took place," Kimball said.
He claims to have receipts to prove this, but could not provide 9NEWS with copies.
"I delivered beef to some clients in the Phoenix area and they paid with a check and there [are] canceled checks that are available and I have a copy of the receipt I gave them for the beef and credit card transactions showing my route down to New Mexico to Arizona and then across to California and then back," he said.
Kimball acknowledged investigators' doubts about what the receipts prove.
"They think it is possible that I might have driven back to commit this murder and then back down to be where I was at, which doesn't make any sense to me," Kimball said.
Powell's family member tells 9NEWS she wants to see whoever killed her receive the harshest sentence possible.
"The death penalty. No less," said Dachelle Powell, Catrina's former sister-in-law.
Dachelle Powell wants people to remember Catrina Powell's life.
"She was happy all the time. She always tried to be positive and optimistic. She was enjoyable to be around. She loved kids," Dachelle Powell said. "I cared about her more than I think most of her family cared about her."
She acknowledged Dachelle Powell had a troubled life and spent time in prison.
When Catrina Powell got out of prison she went to live with her brother. Dachelle Powell was married to Catrina's brother.
The location at the back of the Westminster strip mall where Catrina Powell's body was found differs from where some of the bodies of Kimball's admitted victims were found.
Kaysi McLeod's remains were recovered in a remote area of Jackson County in June 2008. McLeod, 19, disappeared Aug. 23, 2003 from Thornton.
The remains of LeAnn Emry, 24, were found in the Book Cliffs of southeastern Utah on March 11, 2009. She disappeared Jan. 30, 2003. Her car was found abandoned north of I-70 in Utah just west of the Colorado/Utah border.
Remains thought to be those of Terry Kimball, 60, Scott Kimball's uncle, were found near Vail Pass in June 2009. He disappeared Aug. 1, 2004 from his home in Adams County.
The remains of fourth victim, Jennifer Marcum, have not been found. Marcum, 25, disappeared in Denver on Feb. 17. 2003. Her abandoned car was found in a Denver International Airport parking lot.
Kimball pleaded guilty to two counts of second-degree murder and admitted, not to the actual killings of each person, but to taking part in the murders.
Kimball refused to tell 9Wants to Know what role he played.
Kimball has claimed he knows the general area where Marcum's remains lie, but has been unable to show investigators the location.
Have more information about this story, e-mail investigative reporter Jace Larson at email@example.com or call 303-871-1432. Follow him on www.twitter.com/jacelarson.
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