culprit

noun

Etymology: From Anglo-Norman cul. prit, contraction of culpable: prest (d'averrer nostre bille) 'guilty: ready (to prove our case)', words used by prosecutor in opening a trial, mistaken in English for an address to the defendant. See culpable. It may have been influenced by Latin culpa (“blame, fault”).

1. The person or thing at fault for a problem or crime.

   “I have tightened the loose bolt that was the culprit; it should work now.”

   “Another sits beneath the purple canopy—a lady, but alone. The diadem is on her cold and haughty brow; there is no pity in her stern aspect, and the smile on her lip bodes death. Before her stands the lovely culprit, whose fatal beauty, and still more fatal love, are about to be dearly requited.”

2. A prisoner accused but not yet tried.