Fort Collins police recently interviewed a young girl they suspected had been sexually abused, but she wouldn't talk.

On they way out, the cops gave her and her mother a copy of their colleague Sgt. Jon Holsten's book, "The Swimsuit Lesson," in which he explains to children that they should never be touched on any part of their body covered by a swimsuit.

On the way home, her mother noticed the girl in the back seat with her eyes closed, starting to cry. "What's wrong, honey?" the mother asked.

"I need to tell you everything," she said.

They returned to the police station, where she confided to the police exactly what had happened.

Why the change? She said, "Well, the little girl in the book didn't get in trouble by telling, so I figured I wouldn't either."

Holsten, when told that story, knew that the long hours and hard work and travel he'd done for his book was worth it.

Holsten's book, which he self-published four years ago, has sold more than 10,000 copies across the country and in Canada.

On his own — without an agent, a publisher or a publicist — he's managed to put the instructional, beautifully illustrated children's book into 600 elementary schools throughout New York City, and into school districts in Texas, Wyoming, Georgia and parts of Canada.

Holsten got the idea for the book while he was a detective. "About 85 percent of my caseload was child sex crimes," he said. "I was blindsided by the number of cases dropped on my desk. Parents have no clue how often these cases happen. And many don't know how to approach it with their kids. I found a simple way to address a complicated issue."

And it's not just for kids. A 90-year-old woman who saw Holsten on ABC's "Good Morning America" four years ago told her family for the first time that she'd been sexually abused as a child, he said.

Holsten, a 39-year-old father of six kids between the ages of 2 and 14, who works full-time on the midnight shift, has struggled with his project. He had to take out a second mortgage on his house to cover the $25,000 bill for printing and other expenses.

"I've been amazed. Most speakers average sales of their book to about 10 percent of their audiences," Holsten said. "I've been averaging 85 percent. But it's been very difficult to find an agent or a publicist. I don't know why."

Mike McPhee: 303-954-1409 or mmcphee@denverpost.com

Teaching kids about sex abuse

For more information about the $15.99 book, visit theswimsuitlesson.com.