Hooray for Mrs. Gooch, Ms. Brown and the other librarians, front line defenders of our book heritage.
From the judges summary of the facts (my emphasis added)
Mrs. Gooch had realized that, due to the department's security measures, Lipka and Borsuk could not re-enter the Special Collections Department from the elevator, and she had begun to free herself to call for help. She yelled to Susan Brown that they were being robbed, and Ms. Brown wheeled around to pursue the robbers.
She caught up to them in a stairwell where they were attempting to open the emergency exit and, surprised by her arrival and aggressive confrontation, they dropped several objects - specifically, the two remaining volumes of the Birds of North America four-volume set (they had left two volumes atop the pink bed sheet in the Special Collections Department) and the two volumes of the Quadrupeds three-volume set (one of the three volumes had been left behind, stuck in its drawer in the Special Collections Department). Lipka and Borsuk fled through the emergency door carrying five objects (Hortus Sanitatis, the 20 pencil drawings, Synopsis of the Birds of North America, Origin of Species, and Illuminated Manuscript), with Ms. Brown and other librarians in hot pursuit.