Responsa for Sanhedrin 53:7
והלכתא כוותיה דאביי ביע"ל קג"ם
or where he was disqualified on thegrounds of robbery.<span class="x" onmousemove="('comment',' Here again the argument that it is an anomalous procedure no longer holds good. It should be observed that, strictly speaking, the term Zomem is inapplicable in that case, but it is here used rather loosely in the sense of a witness proved to have been ineligible. Tosaf. however, gives this explanation: A and B attested a certain act, claiming that they had witnessed it together, whereupon C and D declared A a Zomem, but leaving the testimony of B unaffected. Now, in point of fact, since A and B jointly testified, they both (including B), deny the allegation of C and D, and therefore it is an anomaly that credence is given to the latter pair. Here, however, B too was proved to be incompetent, though on other grounds, viz., robbery; therefore it is no anomaly that the testimony of C and D against A should be accepted. ');"><sup>7</sup></span>
Teshuvot Maharam
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.