On Aug. 15, 1975, 8-year-old Gretchen Harrington was walking to Bible school from her Marple Township home, writes Kim Douglas for Main Line Today.

She never arrived. Her body was discovered two weeks later.

Joanna Falcone Sullivan and Mike Mathis were 9 years old at the time, living in Marple.

Now their story is captured in their new book, Marple’s Gretchen Harrington Tragedy: Kidnapping, Murder and Innocence Lost in Suburban Philadelphia,

Falcone’s family had moved to Marple from South Philly, imagining a life in the picturesque, safe suburbs.

She was at the swim club the day Gretchen disappeared. Everyone in the neighborhood was affected but it didn’t even make the news, she said.

The prime suspect died in jail serving time for crimes against other children, but he wasn’t convicted in Gretchen Harrington’s murder.

“The ’70s was an era of serial killers—a crop of them. A lot of women and girls disappeared,” said Falcone Sullivan.

People are still talking about the case today in long Facebook conversations.

For the book, Falcone Sullivan and Mike Mathis collaborated remotely with a phone call every Tuesday.

“We’re hoping the book will help solve the case,” she said.

Read more of the interview with Joanna Falcone Sullivan about this unsolved murder in Main Line Today.