The secrets of the old Deer Lodge prison are being illuminated at last.

Helena historian Ellen Baumler and photographer J.M. Cooper have just released a new book, “Dark Spaces,” which chronicles the history of the building and those who lived and died within its walls.

“It’s a dark chapter, but it’s never really been told very well,” says Baumler, who first became interested in the prison in 1981 after reading a Historic Structures Report on the building.

“I thought to myself, somebody needs to do something,” says Baumler. “I just knew that it would be a story that would be interesting to people.”

“It’s just a place that has a very sad, violent history,” she added.

Cooper’s fascination with the prison began a few years earlier, when he landed a special tour of the facility while it was still in use.

“It really impressed me,” says Cooper, who actually happened to run into a couple of former school mates who were doing time during that tour.

“It’s just a weird place,” he says.

The two Montana Historical Society coworkers began talking about collaborating on a project centered on the prison in 2005 and in 2006 received a grant to move forward with the idea.

Built entirely with prison labor, Baumler says the penetentiary’s unusual history begins with its exquisite architecture, which was overseen by a Scottish stone mason and colorful character named James McCalman.

In fact, one resident of Deer Lodge told Baumler that while growing up, she felt as though she was living in the shadow of Cinderella’s castle. The facility was later enhanced with a well-appointed theater, which was used by both prisoners and community members alike.

“The Montana prison was a model,” says Baumler. “It was touted as the best facility of its time.”

But the prison’s external beauty was not mirrored on its inside.

“The living conditions were horrendous,” says Baumler, who notes that there was no running water and that the place was freezing in the winter and sweltering in the summer.

In their research, Baumler and Cooper discovered a subterranean hole that was used to isolate prisoners who misbehaved, and where one such prisoner died.

The duo got permission to view and photograph the so-called “death tower” — the site of a gruesome murder-suicide — as well as several other areas of the prison generally not open to tourists.

Incredibly, Baumler says that living conditions for female prisoners were even worse: Their small, separate facility was surrounded by a high wall and, unlike the men, they were not permitted to exercise outside or do anything other than sit in their tiny cells and serve their time.

“They could see nothing but sky,” says Baumler, who has included several of the women’s stories in “Dark Spaces.”

“Today, these women probably wouldn’t have been convicted of the crimes they supposedly had committed,” Baumler added.

Complementing Baumler’s telling of the prison’s dark history are Cooper’s black-and-white photographs of the facility, inside and out.

Cooper says the project is in line with his continuing effort to document “the part of Montana that’s vanishing.”

“This is a perfect example,” he said.

Baumler and Cooper hope the book will encourage people to make the trip to visit the historic facility, which now operates as a museum and struggles to make ends meet.

The Old Montana Prison is open daily and offers both guided and self-guided tours for a small admission fee.

Although they were never afraid during the time they spent at the prison, both Cooper and Baumler say the building has a decidedly “weird” vibe; and Baumler says that the ghosts of those who did time there are still very much present.

“It is a noisy place,” she says. “You can hear the doors clang and stuff when nobody is around.”