When Pamela Davis agreed to wear an FBI wire in late 2003, she became a key part of the investigation that culminated in the arrest of Illinois Gov. Rod Blagojevich for allegedly trying to sell President-elect Barack Obama's Senate seat.
The extent of Davis' role as a whistle-blower and FBI informant exceeded her expectations.
"I had my suspicions that it would go all the way up to the level of the governor," Davis told ABC News in her first television interview. "Though, I did not have personal knowledge that he was involved."
Watch "World News with Charles Gibson" TONIGHT at 6:30 p.m. ET to hear Person of the Week Pamela Davis, in her own words.
Davis' connection to the investigation began in 2003 when she was president and CEO of Edward Hospital in Naperville, Ill. While working to win approval from the state health planning board to expand her facilities, Davis says she received warnings that she would only gain approval if she used a specific, politically connected contractor and investment firm.
"I got a phone call from one of the 'bad guys' who told me that I should not be presenting my project," Davis said. "And I said, 'well thanks for the information' and basically got off the phone very rapidly and really kind of just ignored his call."
"I was outraged that something as important to me as health care, something that was required, such an important service would have to fall under this type of terrible delay and expense and really just corruption," Davis said.
Ignoring the "pay to play" demands, Davis selected a different contractor, and her initial proposal was subsequently denied.
"Immediately I felt that there was something very, very wrong. And it was right at that moment that I made the decision that I should call the FBI. I felt something was seriously amiss," she said.
Davis took her suspicions to the FBI, sparking a high-stakes operation led by U.S. Attorney Patrick Fitzgerald's office into the heart of Chicago's political corruption.
"Very rapidly it became very obvious to me that this corruption was fairly significant and deep and widespread," Davis said.
The agents asked the grandmother of six to wear a wire.
"For females you typically wear it in your bra. And that is where I wore it," Davis said. "Initially, I was afraid it would somehow become known that I was wearing it. Over time it became much more normal. I actually think that I became fairly good at it."
Agents wired Davis, her office and home phones, and listened to her conversations from a van in the hospital parking deck. Davis worked undercover with the FBI for about eight months. Each of her conversations about the pay to play hospital negotiations uncovered more about the web of political corruption that consumed Chicago.
"I could definitely sense a feeling of much more seriousness about the situation than when I had met with them previously in their office," Davis said, after her first time wearing a wire.
The probe into the health planning board would soon expand, exposing other allegedly corrupt political dealings in the state, and ultimately, over five years, catching references to the governor's alleged involvement in corrupt deals.
"They felt they were so smart and powerful that whatever they attempted to do was well within their control and they would never be stopped," said Davis. "The rapidity of repeating really obnoxious criminal acts and the ease with which they seemed to do it never ceased to amaze me."
Davis says civic responsibility compelled her to "do the right thing," at times sacrificing her own health and well-being.
"I found I became exceedingly secretive and isolated during this time and probably more so than I even recognized. I spent a good deal of time really in isolation to protect innocent people," Davis said.
Davis hopes that her stint as an undercover FBI informant will help change the nature of Chicago politics, putting an end to the widespread machinery systems that have propagated corruption for so long.
When Blagojevich was arrested by Fitzgerald for allegedly trying to sell the seat, Davis felt "vindicated for all of those meetings" in which her hospital plans were rejected and competitors "were not so silently chuckling."
"I felt for the first time somewhat vindicated for the humiliation we have experienced over the last five years," she said.
The Illinois House voted to impeach Governor Rod Blagojevich today and now the vote will move to the state Senate, where a trial will be conducted to remove Blagojevich from office. Davis says the governor should step down immediately.
"I really think he should step down immediately so that the state of Illinois can begin to function more appropriately and to go about doing the business of the state of Illinois for all of its citizens," she said.
Davis says that citizens who believe in good government should take this is a lesson to stand up to political corruption against all odds.
"I believe society is a better place if each of us as individuals tries to be a good citizen. And that means more than simply following the rules. But if I in fact see something that is not right or corrupt, I do feel that it is my responsibly to stand up and really work to try and correct those issues."