From: Rabbi Moshe Sofer
To: Rabbi Yozpa
When two people jointly steal an item and one becomes wealthy while the other remains insolvent, the Chasam Sofer rules that the extent of the wealthy thief's liability depends on who physically lifted the stolen item, whether the goods were immediately divided, and whether the stolen property still exists. The partner-thief is disqualified as a witness not due to self-incrimination but because he is a nogeia b'eidus, preferring to owe his fellow thief rather than the victim.
Source: Shu"t Chasam Sofer CM §133