The verses “If a man steals an ox or a sheep... If being found will it be found the stolen article in his possessions, whether an ox, a donkey, or a sheep, live, he shall pay twofold”  are expounded as amplification-limitation-amplification:

“Being found” and “will it be found” includes everything, and limitations ox, donkey, and sheep exclude one thing each: ox excludes land, donkey excludes slaves, and sheep exclude legal documents from twofold payment. 

“If being found will it be found” excludes  from the twofold payment one who incriminates himself. Even if witnesses do come after his confession, he pays only what he stole.