What is the effect of admitting that codefendants had been charged with assault prior to the assault?

In this case, the admission of the evidence of the codefendants' prior arrests must be deemed prejudicial error, given the fact that the record reveals a close and difficult credibility determination for the jury which had to weigh divergent and conflicting factual recitations describing the fight. The jury took several days of deliberation to reach its verdict. But for admission of the prior arrests, it is reasonably probable that the jury would have believed defendants' version of the events and rendered a more favorable verdict. (See People v. Wagner (1975) 13 Cal.3d 612, 620-621, 119 Cal.Rptr. 457, 532 P.2d 105 (prosecutor's misconduct in implicating defendant in prior criminal acts); People v. Watson (1956) 46 Cal.2d 818, 836, 299 P.2d 243.)