For years, she's been the woman reporters turn to for aid with their SEPTA-related stories.
Now, she'll be providing readers with her own written words -- of the crime fiction genre persuasion.
"It is based on a real FBI investigation," said SEPTA director of communications Jerri Williams, 58, a former FBI agent, of her novel "Pay to Play."
"Ten to 20 percent of it is real, and the rest is all my imagination."
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Williams, who has served at SEPTA for seven years, will step down from her job at SEPTA on Nov. 25.
She has an agent for the book she spent about four years writing, and is now going to focus on getting it into the hands of a publisher.
PR copy for Pay to Play reads, "When a female FBI agent investigating corruption in the Philadelphia strip club industry is blackmailed by a one night stand she picks up in one of the clubs, how far will she go to stop him from destroying her career…and her marriage?"
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Williams, who counts Dennis Lehane, Gillian Flynn and Tom Wolfe among her favorite writers, said she was inspired by work of her fellow agents.
"There were two friends of mine, female FBI agents working this case in the late 90s and early 2000s that involved an L&I inspector and strip clubs," Williams said. "I was just fascinated that these two young ladies were going in and out of strip clubs meeting strippers, strip club owners. I was listening to their stories, and I said, 'This is a book.'"
Williams is already working on her next book. But she said she will miss SEPTA -- even though she rated it as being about as stressful as FBI work, where she worked on economic crimes for 26 years.
"I absolutely love this job," she said. "It's nonstop. It really is similar to the FBI, but I get more cases."