A former FBI agent says a serial killer who doubled as an FBI informant for years manipulated agents into believing he was helping them, all the while preying on unsuspecting victims.
Scott Kimball will likely spend the rest of his life in a federal prison in Colorado after he was sentenced to 70 years in 2009. He pleaded guilty to killing four people between 2003 and 2004, and his number of victims could be much higher, according to former FBI Special Agent Jonny Grusing.
"He made a game out of tricking the FBI," Grusing told Fox News Digital, adding that Kimball's case was unprecedented. "As long as he won the game in front of him, that's all that mattered."
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"To have someone who enjoyed manipulating us, putting stuff in our files, and then making people disappear was beyond anything I'd seen," Grusing said.
Kimball, now 58, was a known serial fraudster who spent time in and out of prison during his youth and early adulthood. In the 1990s, he practiced working the criminal justice system, becoming an informant for local police and blaming his own crimes on cellmates.
After a 2001 arrest for check fraud in Alaska, he befriended his cellmate Steve Ennis, who had been charged in a drug case. To snake his way into a role as an FBI informant, a calculated Kimball convinced Ennis that he could make the drug case go away, and that he had powerful connections that could have witnesses "taken care of." During the jail stint, he also befriended Ennis' girlfriend, a stripper named Jennifer Marcum.
After planting the seeds of a murder-for-hire plot, Kimball reported to the FBI that Ennis was planning to have witnesses killed, and shortly thereafter, was granted confidential informant status. He was moved to a lower-security prison and eventually released.
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"Our primary victim in our case was Jennifer Marcum," Grusing said. "Mainly, he convinced Steve [Ennis] to hook him up with Jennifer to get Jennifer out of stripping. So, at the same time he's making Steve look like the bad guy, he's taking Jennifer and isolating her and killing her."
By February 2003, Scott was a bona fide informant operating throughout the western United States, and Marcum was dead.
During his several-year span as an informant, Kimball was responsible for killing four people, including Marcum. He would later confess to killing at least 21 people, and according to Grusing, told his own attorneys, he was responsible for 45 to 50 killings. His other alleged victims all remain unnamed.
After his eventual arrest, authorities would learn that Scott killed LeAnn Emry, another stripper, whom he shot and left for dead in a remote desert area, just one month prior to Marcum's murder.
In August of that year, Kayci Mcloed went missing. Her murder was eventually linked to Kimball, and he confessed to it.
In 2004, Kimball killed his own uncle, Terry Kimball.
In each case, the serial killer provided "breadcrumbs" to the FBI that ended up in the case files, including that he was the last person to be seen with two of the victims.
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In 2006, pressure from victims' family members forced the FBI to begin investigating its own informant.
"And that's when two dads came to the FBI office to talk to my boss and say, not only was Scott responsible for Jennifer's disappearance, but another girl named Kayci was last with Scott, and that reporting was in the case file," said Grusing. "But Scott had mastered such that, again, he enjoyed the game, and it was like leaving little breadcrumbs to say, 'I'm so good at this, I can tell you about these homicides, and you'll never know I'm doing them.'"
In March of 2006, Kimball was arrested in California on fraud-related charges.
While he was in jail, the FBI built a case against him, and in 2009, he was officially charged with the murders.
But the killer's manipulation of the FBI continued for years, as Grusing and others tried to get him to give up the locations of his victims' remains.
"We knew he was manipulating us, pointing us in different directions, but he's the only one who knew what happened to them," said Grusing. "So even though it was painful to be in front of him and let him win all the time, as long as he thought he was squirming, he would always talk. So that's how I stayed with this man for 15 years."
Eventually, McLeod and Emry's remains were recovered.
At one point during Grusing's decade-and-a-half quest to get justice for more of Kimball's victims, the killer asked him why he had never been named like other serial killers.
Grusing asked what name Kimball would give himself.
"He said, 'The Opportunity Killer, because I just kill people when I have the opportunity.'"
Marcum's remains have never been found.
