“An earprint is an impression of the external ear. House breakers may leave their earprints inadvertently when they listen at doors and windows to check if there is anyone inside before breaking and entering a premises. Owing to uniqueness and individualistic characteristics of the human ear, earprints can be used as evidence to link a criminal with the crime. In the recent past, many suspected thieves have been convicted and several burglaries linked due to the presence of similar earprints.”
So writes Professor Kewal Krishan of Panjab University, India, in ‘Identification: Prints – Ear (Earprints)’, in the Encyclopedia of Forensic and Legal Medicine (Second Edition) 2016. [At the time of writing the book is on special offer at $1,375.00 – down from its usual list price of $2,100.00]
As an alternative, you can find out more about earprints via ‘Earprint recognition based on an ensemble of global and local features’ Security Technology (ICCST), 2015 International Carnahan Conference on. A copy of which may be found here, free of charge : 
“The earmarks are usual evidences in many real criminal investigations. The earprint appears for example when a criminal tries to listen through a window or a door before entering, and the methods to make it visible are similar to those used in latent fingerprint lifting. However, its acceptance as evidence in real prosecutions still raises doubts. Although it is well-accepted the uniqueness of the ear and its usefulness for person identification, the permanence of such discriminate ability in earprints is not obvious.”
Some of the doubts outlined above might arise from consideration of stories such as this one from The Guardian, 2004. ‘Earprint landed innocent man in jail for murder’
Also see : Unconstrained ear recognition progress