Origin of red-handed
- Earlier red-hand with the hands red (from blood)
From American Heritage Dictionary of the English Language, 5th Edition
- To be taken with red hand in ancient times was to be caught in the act, like a murderer with his hands red with his victim's blood. The use of red hand in this sense goes back to 15th-century Scotland and Scottish law. Sir Walter Scott's Ivanhoe (1819) contains the first recorded use of taken red-handed for someone apprehended in the act of committing a crime. The expression subsequently became more common as caught red-handed.