What is the test for a motion to sever a jointly-filed murder case?

discretion in ruling on a severance motion is guided by the nonexclusive factors enumerated in People v. Massie (1967) 66 Cal.2d 899, 917, such that severance may be appropriate 'in the face of an incriminating confession, prejudicial association with codefendants, likely confusion resulting from evidence on multiple counts, conflicting defenses, or the possibility that at a separate trial a codefendant would give exonerating testimony.' " (People v. Coffman and Marlow (2004) 34 Cal.4th 1, 40.) "We review the denial of a severance motion for abuse of discretion, based on the facts as they appeared at the time of the court's ruling." (People v. Winbush (2017) 2 Cal.5th 402, 456.)

" 'In determining whether a trial court's refusal to sever charges amounts to an abuse of discretion, we consider four factors: (1) whether evidence of the crimes to be jointly tried is cross-admissible; (2) whether some charges are unusually likely to inflame the jury against the defendant; (3) whether a weak case has been joined with a stronger case so that the spillover effect of aggregate evidence might alter the outcome of some or all of the charges; and (4) whether any charge carries the death penalty or the joinder of charges converts the matter into a capital case.' [Citation.] 'We then balance the potential for prejudice to the defendant from a joint trial against the countervailing benefits to the state.' [Citation.] However, '[i]f the evidence underlying the joined charges would have been cross-admissible at hypothetical separate trials, "that factor alone is normally sufficient to dispel any suggestion of prejudice and to justify a trial court's refusal to sever properly joined charges." [Citations.]' [Citation.]" (People v. Westerfield (2019) 6 Cal.5th 632, 689.)