Frances Glessner Lee grew up in the Gilded Age as the heiress to a fortune made in industrial farm equipment. Her childhood was “sheltered and indulged.” She would marry at age 20, have three children, and then, in a turn against convention, divorce her husband.

It was in her 40s—free of a husband and then free of a brother and father who both died, leaving her a vast fortune—that Lee embarked on the project that would consume the rest of her life. She had become enthralled by the grisly crime stories of George Burgess Magrath, her brother’s friend and a medical examiner in Boston. And so Lee began pouring her family fortune into a project that combined the very unladylike world of crime with the domestic arts: the Nutshell Studies of Unexplained Death.

The nutshells are dioramas, based on actual death scenes that Lee painstakingly researched. (“Convict the guilty, clear the innocent, and find the truth in a nutshell” went a police saying at the time.) Lee finished 20 nutshells before her death in 1962. Eighteen are still used today by Maryland’s Office of the Chief Medical Examiner to train detectives to look for clues, one was destroyed in transit, and the last “lost” nutshell has been recovered from an attic and restored for an upcoming exhibit of Lee’s work at the Renwick Gallery of the Smithsonian American Art Museum in Washington, D.C.

Lee was fastidious—to the point of obsession. In one nutshell titled “Saloon and Jail,” a man lies facedown in the street. Debris is strewn on the pavement: miniature cigarettes (hand-rolled and filled with paper), a banana peel (painted leather), scraps of paper with visible faces. A storefront in the background displays newspapers and magazines with real covers from the date of the man’s death. A bucket of tiny, colorful lollipops sits under the magazines, each piece of candy individually wrapped in cellophane.

The story goes that at one point Lee requested the carpenter who built the wooden structures and furniture in the nutshells remake a certain rocking chair: She wanted it to rock the exact same number of times as the rocking chair in the real-life scene. Lee also made use of factory-made dollhouse pieces, like the boxes of Ivory soap that show up on the pantries of various nutshells. But the textiles—from clothing on dolls to upholstery on couches—she hand-sewed all by herself. After her death, people found half-finished doll clothing that Lee was knitting with pink yarn and straight pins.

For Lee, the nutshells were more than just objects for display. They were part of a campaign to bring rigor to forensic science—a campaign, ultimately, for justice. She funded the Department of Legal Medicine at Harvard Medical School, with her friend George Burgess Magrath as its first professor. And she hosted seminars using the nutshells to teach police how to examine crime scenes.

As a high-society woman, Lee knew how to throw memorable parties to woo men who might not be so inclined to listen to a middle-aged woman. At the end of her seminars, she wined and dined them at the Ritz Carlton. The parties featured china specially made for the occasion. And she left them with a parting gift—a miniature nutshell that opened to reveal a pair of miniature, working cufflinks.

“You can’t buy a doll in rigor mortis.”

“People didn’t know where to put her,” says Nora Atkinson, the Smithsonian curator who organized the Lee exhibit. Lee was a woman in a man’s world, who had succeeded by marshaling her talents in the traditionally feminine pursuits. She won respect in professional circles. At one point, New Hampshire made her an honorary police captain. But she was still seen first as a “grandmother” with murder as a “hobby.”

Lee knew that to be taken seriously, her nutshells had to be more than just meticulously crafted. They had to be scientifically accurate. She bought porcelain doll heads and other parts, but she made sure to fashion their bodies according to real biology. “You can’t buy a doll in rigor mortis,” says Ariel O’Connor, a Smithsonian conservator who has been working on the nutshells. In one nutshell, a woman has fallen into a position with an unusually stiff neck—a sign she may not have died in this position. Some dolls show lividity, which is when blood in the body sinks to whatever part of the body is facing down, turning the skin purplish red. It can also hint at whether a body has been moved. The dolls dead by hanging were filled with lead shot, to give them the heft of real human bodies.

For all the care in creating them, the 80-year-old nutshells are showing their age now. Tablecloths have faded. The blood on the bodies, which O’Connor suspects to be red nail polish, has darkened to a less realistic deep purple.

To prepare the nutshells for exhibition at the Smithsonian, O’Connor has led a months-long effort to conserve the dioramas. The work, she says, has been a bit like detective work itself. She looks for subtle hints like glue residue to match up, say, an object that has fallen off of the shelf where it originally stood. Because any object out of place can in fact be an important clue to the murder, every move requires consultation with Maryland’s medical examiners, who have the solutions to the nutshells.

“It is one of the most challenging things I have ever tried to work on,” says O’Connor. The sheer number of materials in the nutshells add to the challenge. Materials have “inherent vice,” or a natural tendency to degrade over time. The plastic panes of the nutshells’ windows, for example, are especially prone to warping. O’Connor also had to figure out how to preserve a nutshell that features a burnt house. (Lee literally had a blowtorch taken to it.) She ended up borrowing techniques from archaeology used to preserve burnt wood.

A big part of the conservation project has focused on lighting. Lee used the incandescent bulbs available in her time, which cast a beautiful warm glow but have the disadvantage of heat. Heat causes damage. The painted linoleum in one nutshell had cracked and curled, in part, O’Connor thinks, because of the heat of the lightbulb above it.

To be in the Smithsonian exhibit, the lights would have to be on hours each day, which would have caused too much damage. So the team replaced 70 incandescent bulbs with custom-made LEDs, matching the quality of light without the heat. It’s possible now because of recent advances in LED technology. “Just a few years ago, we couldn’t have achieved this quality with LEDs,” says Scott Rosenfeld, a lighting designer at the Smithsonian. The 80-year-old dioramas now have a state-of-the-art lighting system.

The trickiest nutshell to restore was the lost nutshell, which features a dead man on his couch. The solution is completely lost. To make matters worse, when it was taken out of the attic where it was found, it was tipped over, displacing many of the objects Lee had carefully placed inside as clues. There was dirt all over the living-room floor. The bannister for the stairs had fallen down, which led some to suspect it was the murder weapon. But then O’Connor discovered that the bannister is supposed to be intact. They glued it back on.

When I stopped by the unfinished exhibit, O’Connor and Atkinson were still discussing where to place an object that had come loose and they suspected was a key clue. (I’m being purposely vague to avoid spoilers. I will say, you would have to look very, very carefully to even notice.) I asked O’Connor if she had solved the death after spending so many hours with the lost nutshell. She laughed and demurred. Visitors to the Smithsonian’s Renwick Gallery will have the opportunity to test their own detective skills.

The Renwick Gallery specifically showcases craft and decorative arts. Atkinson told me she was particularly pleased to exhibit Lee’s nutshells because museums have traditionally focused on studio craft, which has been so dominated by the work of white men. Half a century after her death, Lee is still transgressing in the world of men.