I'm not sure if there's a specific meaning but I would guess that an impossible crime is one in which there are no clues left behind at the crime scene.
Whether what's left behind is tangible physical evidence, or a snapshot of the criminal's psychological make-up, Locard's exhancge principle dictates that it's highly difficult not to leave behind traces of one's presence.
In truth, rather than trying to remove all evidence form a crime scene, for criminals an easier way might be to use Locard's exhcange principle to their benefit by planting distractionary evidence to cover over their presence.
Good question
I'm not sure if there's a specific meaning but I would guess that an impossible crime is one in which there are no clues left behind at the crime scene.
Whether what's left behind is tangible physical evidence, or a snapshot of the criminal's psychological make-up, Locard's exhancge principle dictates that it's highly difficult not to leave behind traces of one's presence.
In truth, rather than trying to remove all evidence form a crime scene, for criminals an easier way might be to use Locard's exhcange principle to their benefit by planting distractionary evidence to cover over their presence.
I think impossible crime is to murder oneself and get away with it where nobody suspects about anyone at all.