BOCA RATON, Fla. — In December 2016, law enforcement agents seized computers and hard drives from the home of Tay Christopher Cooper, a retired high school history teacher, in Carlsbad, California. On the devices, digital forensic experts found more than 11,600 photos and videos depicting child sexual abuse, according to court documents.
Among the videos was one showing a man raping a toddler girl, according to a criminal complaint.
“The audio associated with this video is that of a baby crying,” the complaint states.
Police were led to Cooper’s door by a forensic tool called Child Protection System, which scans file-sharing networks and chatrooms to find computers that are downloading photos and videos depicting the sexual abuse of prepubescent children. The software, developed by the Child Rescue Coalition, a Florida-based nonprofit, can help establish the probable cause needed to get a search warrant.
Cooper had used one of the file-sharing