Suppose that a District Attorney receives from a County Attorney (of a county in his district) information pertaining to misappropriation of county property, for use in presenting the matter to a grand jury, and that later, no indictment being returned, the County Attorney files a civil suit on behalf of the county against a county official and the surety on his fidelity bond, alleging such misappropriation. Would it be unethical for the law firm of which the District Attorney is a member to represent the surety in such civil suit?
23 Baylor L. Rev. 827 (1972)
CONFLICTING INTERESTS - DISTRICT ATTORNEY - COUNTY'S SUIT ON FIDELITY BOND
A District Attorney (or his law firm) may not ethically represent the bonding company defendant in a civil suit filed by a county situated in his district for misappropriation by a county official after presentation by the District Attorney of the facts to a grand jury.
Canon 6.
Tex. Comm. On Professional Ethics, Op. 307 (1965)