From: Rabbi Moshe Sofer
To: Rabbi Feish
The Chasam Sofer presents a comprehensive taxonomy of witness disqualification, distinguishing three categories: family relationship, financial interest, and sin. He argues that repentance restores a sinner's qualification without techilaso v'sofo concerns only for non-financial sins, since financial sins require the concrete act of returning stolen property and thus lack the "in one's power" condition, while offering a novel exegetical proof from Shemos 23:1 to support this distinction.
Source: Shu"t Chasam Sofer CM §36