DENVER – A former FBI agent reveals that a serial killer, who served as an FBI informant for several years, deceived agents into thinking he was assisting them while targeting unsuspecting victims. 

Scott Kimball will likely remain in a federal prison in Colorado for the rest of his life following a 70-year sentence in 2009. He admitted to killing four individuals between 2003 and 2004, and his victim count could be much higher, as per former FBI Special Agent Jonny Grusing. 

“He turned tricking the FBI into a game,” Grusing shared with Fox News Digital, stating that Kimball’s case was unparalleled. “Winning the game in front of him was all that mattered to him.”

In 2006, pressure from victims’ family members forced the FBI to begin investigating its own informant. 

“And that was when two fathers approached the FBI office to speak to my superior, claiming Scott was responsible not only for Jennifer’s disappearance but also for a girl named Kayci, who was last seen with Scott, as documented in the case file,” Grusing mentioned. “Scott’s mastery allowed him to enjoy the game, leaving small hints to illustrate his expertise, implying, ‘I’m so proficient at this, I can reveal these homicides, and you’ll never suspect I’m the perpetrator.'”

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.