Mary Casanova was paging through a book of local history a few years ago when she happened upon a heart-stopping anecdote: In the early 1900s, a prostitute in the northern Minnesota town of Northome had died in the snow, and someone thought it would be amusing to drag the frozen body into the City Council chambers and stand it in a corner.

That was all the book said -- no mention of the woman's name, or why she had collapsed that cold, bitter night, or what happened to her body later. Just that one sad paragraph, which haunted Casanova for years.

"It wouldn't let me go," said Casanova, who lives near International Falls, Minn. She wanted to write about it, but she wasn't sure how; Casanova has built a career as an award-winning author of books for children, and a gruesome story about a mocked, long-dead prostitute seemed an inappropriate fit.

"For a long time I kind of danced around it," she said. "And after 10 years of talking about this novel, finally someone in my writers' group said, 'Mary, just write the damn thing.'"

And that is how "Frozen" came to be. Out this month, it's her 30th book and the first original young-adult novel to be published by the University of Minnesota Press.

Casanova was born in Duluth and grew up in Arden Hills, the fourth of 10 Gazelka kids and one of three girls. In a family that big, it's easy to get lost in the crowd. Becoming a writer "was my way of being heard," she said.

From the time she was a child, Casanova loved the wild north. Her family had the use of two wilderness cabins -- one from each set of grandparents -- and on weekends they piled into the station wagon and headed for the woods. The cabin near Ely had electricity and a TV set; the cabin near Cook, however, was tiny and sweet, accessible only by boat and lit by gas lamps. "That was the one we loved," Casanova said. "It was so rustic, and such a step back in time."

By the time she had graduated from the University of Minnesota, Casanova was sure of two things: She wanted to be a writer, and she wanted to live Up North. "I have a busy mind, and anytime I can get in nature, it quiets me and slows me down," she said. "The wilderness helps me be who I am meant to be."

Casanova's husband, Charlie, took a job at an insurance office in Ranier, on Rainy Lake near the Canadian border, and he and Mary moved into a small house by the water. The move was easy; the writing proved hard. "I had no clue of how you do that, no sense of how you even begin," she said. She had earned a degree in English, but beyond that she had no connections, no network, no real certainty, even, of what kind of writing she wanted to do.

She signed up for a few writing workshops, and when she landed in a Split Rock Arts Program class in writing for children, there was instant clarity.

"It was one of those lightbulb moments," she said. "This is what I'd been looking for and didn't know it." And then she read Gary Paulsen's novel "Hatchet," and thought, "Oh, maybe I have my own North Woods story I could write."

Since then, Casanova has written picture books, chapter books, historical and contemporary young-adult novels, five books for the "American Girl" series and a whole series about dogs.

Fiction infused with history

Casanova searched for years, but never was able to learn anything more about the frozen prostitute in Northome. So instead, she spun her own version of events that stemmed from that bitter night. "Frozen" is a coming-of-age novel about a girl named Sadie Rose who as a small child was found huddled in the snow next to her dead mother.

Casanova crafted the persona of the dead woman carefully, imagining her as a loving mother who was forced into prostitution. She set the novel in the 1920s, a time when women were coming into their own in the big cities. But in a remote border town, "what options did women have?" Casanova said. "There weren't a lot. It was a hard place to be a woman on her own."

The fiction in "Frozen" is buttressed solidly by fact -- not just the frozen prostitute, but the geography and history of Koochiching County, and even some of the other characters. The feuding characters of Victor Guttenberg and E.W. Ennis, for instance, are based on conservationist Ernest Oberholtzer and millionaire mill owner E.W. Backus, both of whom lived on Rainy Lake in the 1920s and had opposing visions for the future of the northern forests. "These are legendary, epic kinds of characters," Casanova said. "My challenge was to not let them take over the story."

A serendipitous mistake

It took 10 years to write "Frozen," with writing time tucked in around other projects, and when she finally finished, Casanova thought hard about what to do with it. Her big New York publishers were hesitant about taking on a serious historical novel set in the middle of nowhere, when the trend in YA is for paranormal romances. ("Glitzy and dark books," Casanova calls them.)

"I had so much heart and passion poured into this story, I didn't want to have it published in order to have it go out of print in six months." She decided to try a regional publisher.

She meant to ask her agent to send "Frozen" to the Minnesota Historical Society Press, but she mistakenly said the University of Minnesota Press, so that's where it went. The UM Press had never published original young-adult fiction, but when acquisitions editor Todd Orjala saw the manuscript, he was delighted.

"Mary's project was a manuscript by a really well established Minnesota author with a really strong track record of doing these books that have regional tie-ins," he said. "Also, Mary was someone I had met, and her picture books were books I had read to my kids. It didn't take long to sort out a deal."

There was a sense of magic about the whole process, Casanova said. "I listen a lot to my inner voice, as a writer and also just out in the world. It just felt like this was the direction to go. So my mistake was, instead, exactly where it needed to be.

"It reminds me that all I can do is write the story that needs to be told. When I get overwhelmed, I ask myself, Is this a story that hasn't yet been told? If I don't tell it, who will?"

Laurie Hertzel • 612-673-7302 Twitter: @stribbooks