Lip prints are a rarely used form of evidence that can be located at scenes of crime. Their potential value was recognized by forensic pioneers, including Locard. Studies have concluded that lip prints are unique, and their persistency over a period of years has been established. This article discusses a lip print comparison that was performed by the author, and recounts a contentious American case in which a homicide conviction was obtained primarily on the basis of lip print evidence. (Published Abstract) Figures and references