Responsa su Levitico 5:1

Q. A claimed that he gave B a coat of mail and thigh plates as security for a loan. He repaid that loan, and therefore demands back his security. B answered that he received from A only a coat of mail which he was ready to return upon the latter's payment of money still due B. Upon hearing B's reply, A said to the judges that he knew that the law required them to charge B with an oath, but that B was not qualified to take an oath since he was a notorious thief and was suspected of swearing falsely. A made a public announcement that whoever knew anything that might disqualify B from taking an oath, should appear and testify before the court and the community leaders, in accordance with the Biblical injunction (Leviticus, 5, 1). Many witnesses appeared, but the testimony of only three persons was valid. One of these testified that B had stolen one pound from him; the second said that B had testified against him in a Gentile court and thus had caused him to suffer damages; and the third testified that B had bound himself by a herem to redeem his pledged horse, and had failed to do so. Since these misdemeanors had happened long ago and B might have repented since then, was the testimony of these witnesses sufficient to disqualify B from taking an oath?
A. B should be disqualified from taking an oath because of the testimony of the first and third witnesses. The Talmud (B. K. 62a) came to no conclusion regarding the trustworthiness of an informer; therefore, the testimony of the second witness is of no consequence.
SOURCES: Pr. 978.