What is the test for a motion for severance of a double murder trial?

If certain circumstances apply, the court may order separate trials. For example, the court may sever the trials if there is an incriminating confession by one defendant that implicates a codefendant, the defendants will present conflicting defenses or when " 'there is a serious risk that a joint trial would compromise a specific trial right of one of the defendants, or prevent the jury from making a reliable judgment about guilt or innocence.' " ( People v. Lewis (2008) 43 Cal.4th 415, 452, 75 Cal.Rptr.3d 588, 181 P.3d 947 ( Lewis ).)

We review the denial of a motion for severance for abuse of discretion based upon the facts as they appeared when the trial court ruled on the motion. Even if a trial court did not abuse its discretion when it denied a motion for severance, we must determine whether the joinder of defendants for trial resulted in "gross unfairness depriving the defendant of due process of law." ( People v. Rogers (2006) 39 Cal.4th 826, 851, 48 Cal.Rptr.3d 1, 141 P.3d 135 ( Rogers ).) In the case of a violation of federal due process, reversal is required unless the state can prove beyond a reasonable doubt the error did not contribute to the verdict. ( People v. Albarran (2007) 149 Cal.App.4th 214, 229, 57 Cal.Rptr.3d 92.)