[1] To this end, she created the Nutshell Studies of Unexplained Death, twenty true crime scene dioramas recreated in minute detail at dollhouse scale, used for training homicide investigators.

Eighteen of the Nutshell Studies of Unexplained Death are still in use for teaching purposes by the Maryland Office of the Chief Medical Examiner, and the dioramas are also now considered works of art.

[9] Glessner Lee was inspired to pursue forensic investigation by one of her brother's classmates, George Burgess Magrath, with whom she was close friends.

She hosted a series of semi-annual seminars, where she presented 30 to 40 men with the "Nutshell Studies of Unexplained Death", intricately constructed dioramas of actual crime scenes, complete with working doors, windows and lights.

[8] The 20 models were based on composites of actual cases and were designed to test the abilities of students to collect all relevant evidence.

The rooms were filled with working mousetraps and rocking chairs, food in the kitchens, and more, and the corpses accurately represented discoloration or bloating that would be present at the crime scene.

[13] As of 2020, the models could be found at the Maryland Office of the Chief Medical Examiner in Baltimore, where they were still used in the annual Frances Glessner Lee homicide investigation seminar.

He wrote a book on the subject, and the family home, designed by Henry Hobson Richardson,[8] is now the John J. Glessner House museum on the near South Side of Chicago.

[18] Many of her dioramas featured female victims in domestic settings, illustrating the dark side of the "feminine roles she had rehearsed in her married life.