From The Cartographers, by Peng Shepherd:
"It was an open-and-shut case, they’d determined. Dr. Young had been alone—the security cameras in the Map Division didn’t turn on until the last employee in the department had clocked out, but they had already been running in the lobby since closing time the night before. The only reported movement was from the security guard on patrol, who had been the one to find him when he’d peeked in on his last loop around the library, sometime in the early hours of dawn."