A former Chicago police officer -- who risked her own safety to help nab a corrupt officer extorting money from the city's poorest and planting drugs on those who refused to pay -- will have her story featured Friday on the CBS series "Whistleblowers."

Shannon Spalding says she's had her tires slashed and was repeatedly threatened while she helped build the case against a corrupt team of officers run by former Sgt. Ronald Watts.

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"Someone was trying to kill me," Spalding said. "When I signed up for this job, I knew I might have to lay my life down, but I never thought I'd have to worry about it being a fellow officer doing that to me."

Spalding, who joined the Chicago Police Department in 1996, said she spent time in some of the city's most violent neighborhoods. To survive, she recalled leaning on veteran cops like Watts.

"I thought he was battling crime and he was doing it with finesse and grace," she said.

But about a decade later, while on an undercover assignment in the narcotics division, she began to see Watts in a different light.

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Spalding said she began troubling rumors as she and her partner would make an arrest, with a suspect saying something along the lines of: "I can't believe you're going to arrest me when one of your own is actually running the narcotics side," Spalding said.

After some digging, Spalding learned the charge was true: Watts and his group would threaten and plant drugs on residents of the Ida B. Wells projects who didn't go along with their rules -- and that type of intimidation had gone on for years.

Spalding was faced with a decision.

"If we don't report this criminal conduct we're absolutely no better than Watts or any of these other corrupt officers. And if we do, we may just be ending our careers and putting ourselves in real danger," she said.

In the end, she and her partner went to the FBI.

"My greatest fear was that because this was such a long-running...criminal enterprise...I felt that we would be set up for dead," she said.

Eventually, though, Watts and one of his officers, Kallat Mohammed, were arrested after they were caught stealing $5,200 from a drug courier -- who also happened to be Spalding's informant and was wearing a wire at the time.

Watts was sentenced to 22 months behind bars while Mohammed received an 18-month sentence.

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Since their arrest, 60 Chicagoans who were wrongfully arrested by Watts and his team have been exonerated.