Stealing an iPhone/iPad could become a bit riskier if Apple implements a recently patented method for collecting and storing pictures/fingerprints of a thief. The patent application explains how Apple would hold on to the biometric information of unauthorized users, which could make stealing a phone risky and even help in prosecution.
This data collection method would rely on the iPhone’s Touch ID module, camera, and other sensors. Different triggers for the collection could be in place, including capturing the data after a single failed authentication attempt. Machine learning could also be employed to more intelligently capture data.