Another origin, occasionally referenced, pertains to a myth that originated in the Northern Ireland province of Ulster. A boat race was called to crown the next king. The first person to touch the shore would earn the honor. One overly determined man cut off his own hand and flung the bloody appendage to shore to ensure his victory. However, the story of his bloody red hand is a myth and is not the origin of the phrase.
TIFO traces that usage's transition from "red hand" to "red-handed" in Sir Walter Scott's Ivanhoe. "I did but tie one fellow, who was taken redhanded and in the fact, to the horns of a wild stag," Scott wrote. Ivanhoe helped the phrase spread throughout the English-speaking world.
It wasn't until later that the full phrase "caught red-handed" was used. The first instance of that appears in 1857 in George Alfred Lawrence's Guy Livingstone. From there it proliferated to the familiar phrase almost everyone has used, including Sponge Bob.