Is there a conflict of interest between counsel for a defendant and a prosecution witness?

defense [citation]. [] The trial court is obligated not merely to inquire but also to act in response to what its inquiry discovers. [Citation.] In fulfilling its obligation, it may ... make arrangements for representation by conflict-free counsel. [Citation.] Conversely, it may decline to take any action at all if it determines that the risk of a conflict is too remote." (People v. Bonin (1989) 47 Cal.3d 808, 836-837.)

In People v. Harris (2005) 37 Cal.4th 310 (Harris), the prosecution moved for a hearing to determine whether a conflict of interest existed between the defendant and his counsel, where counsel's office previously represented a prosecution witness. Before the hearing could be held, the witness died. The trial court determined his death rendered moot the question of a conflict, and, without objection, took the prosecution's motion off calendar. Counsel continued to represent the defendant through the guilt and penalty phases of trial, although the defendant represented himself at the motion for new trial. (Id. at p. 342.)