How did John Dillinger and Roscoe Pitts attempt to change their fingerprints?

John Dillinger (1903–1934) used acid to burn his fingerprints in an attempt to permanently change them by removing the ridge patterns. He failed, and the fingerprints that reappeared were identical to the ones he had tried to change. In a more dramatic attempt to permanently alter his fingerprints, another American criminal named Roscoe Pitts had a plastic surgeon remove the skin from the first joints of his fingers and replace it with skin grafts from his chest. Investigators were able to identify him from his fingerprints and his palm print.