That means that the QuOD is useful for picking out those who show up at crime scenes repeatedly, but also at picking out faces in areas documented with multiple security cameras or personal video recordings. The software counts the number of times a particular face pops up, and if it's more than a certain amount (set by the operating authorities), it'll present that person as a possible person of interest--though it doesn't seem to link to any database, like this FBI face detector does.