The phrase originated in the 1893 Sherlock Holmes book of short stories "The Adventure of the Gloria Scott".

"Then we rushed on into the captain’s cabin, but as we pushed open the door there was an explo- sion from within, and there he lay with his brains smeared over the chart of the Atlantic which was pinned upon the table, while the chaplain stood with a smoking pistol in his hand at his elbow." Source, Pg 9, second column

Before this, the term "red handed" was also used, and that came from the basis of a persons blood being on the murderers hands.

"To be taken with red hand in ancient times was to be caught in the act, like a murderer, his hands red with his victim’s blood." Source, Pg175, first column

Another possible term is "In flagrante delicto" which roughly translates from Latin as "In blazing offense".
Source: A Dictionary of Law (2009), Oxford University Press, Jonathan Law & Elizabeth Martin