For hundreds of years, stealing and butchering another person’s livestock was a common crime. But it was hard to prove unless the thief was caught with a dead animal … and blood on his hands, hence – red-handed.
The term seems to have derived from Scotland.
Red-hand appears in print many times in Scottish legal proceedings from the 15th century onward; for example, this piece from Sir George Mackenzie’s A discourse upon the laws and customs of Scotland in matters criminal, 1674:
“If he be not taken red-hand the sheriff cannot proceed against him.”
The earliest known printed version of ‘red-handed’ is from Sir Walter Scott’sIvanhoe, 1819:
“I did but tie one fellow, who was taken redhanded and in the fact, to the horns of a wild stag.”