What method did John Dillinger use to try to remove his fingerprints?

John Dillinger attempted to remove his fingerprints using acid, which was a method motivated by his desire to evade law enforcement. Acid can destroy the skin tissue that forms the unique whorls and patterns of fingerprints, but it is a dangerous and often ineffective method, as it may not completely eliminate the fingerprint ridges. This approach aligns with Dillinger's notoriety as a criminal attempting to evade capture by any means necessary.

While the other options are methods that have been referenced in various contexts for altering fingerprints, acid stands out historically as the choice associated with Dillinger's efforts specifically. Fire, for instance, can severely burn the skin, and sandpaper can physically abrade the skin; however, both methods carry significant risks of scarring and might not fully erase the fingerprint patterns. Laser treatment, a modern method for altering skin, was not available during Dillinger's time.