Murdering a character does not a crime novel make, says Hank Phillippi Ryan.

“You can’t just willy nilly kill someone,” Ryan told a group of mystery readers at the Mattapoisett Library on Friday. “It has to be about more than whodoneit and whydoneit.”

The author of six crime thrillers and winner of numerous mystery awards, Ryan would know. She also has 40 years of experience as an investigative journalist uncovering crime and other issues at Boston’s WHDH 7, for which she’s garnered 30 Emmys.

Crafting a news piece was good preparation for novel writing, said Ryan.

“It’s all about telling a great story,” she said. “At the end you want some justice and some satisfaction. You want to have changed the world a little bit.”

Also like a good investigative report, the essence of a good mystery has to be about uncovering a secret that someone doesn’t want uncovered.

Ryan, 64, didn’t begin writing fiction until age 55. But reading Nancy Drew in a hayloft as a kid, she often thought of one day penning her own suspense novels.

“I fell in love with the architecture of mystery,” she said.

After graduating from college, Ryan worked on political campaigns until landing a job as a radio reporter. She transitioned to television in 1975 and eventually made her way to Boston. Her job and the city provided plenty of fodder for novels, including Ryan’s latest book, “The Wrong Girl.”

The book brings back Boston newspaper reporter Jane Ryland, the main character of Ryan’s previous novel “The Other Woman,” as she looks into an agency connecting birth parents with the wrong kids. The investigation intersects with the mysterious death of a foster parent.

“Sometimes stories that don’t make it onto TV…turn out to be a crime thriller. That’s what happened with ‘The Wrong Girl,’” said Ryan.

An agency that mixed up a parent and child reunion fueled Ryan’s imagination, but was only a jumping off point.

“I work without an outline. The only way I can find out what happens at the end of my book is to sit at the desk,” she said.

Ryan continues to work at WHDH while also writing and said another thriller is due out in fall 2014.

She encouraged her audience at the library to take her as an example. “I followed my dreams. When you think, I wonder if I should do this…just go ahead. I’m the proof that it can be done.”