Does the absence of a witness in the trial of a defendant in a murder case affect the outcome of the trial?

(Louis, supra, 42 Cal.3d at p. 989.) In Louis, the witness's preliminary hearing testimony was the sole evidence identifying the defendant as the shooter; the defendant and his codefendants were tried before separate juries that heard virtually the same evidence, except for the absent witness's testimony, and the codefendants went free while the defendant was sentenced to death; and the witness was "known to be highly unreliable and likely to disappear . . . ." (Id. at pp. 974, 989.) Moreover, in Louis, the prosecutor "may have taken no steps [to prevent the witness's disappearance] because he hoped that [the witness] would disappear," since the witness " 'would not look as good in person as he does in reading out of the transcript . . . .' " (Id. at p. 993, fn. 7; see People v. Thomas (2011) 51 Cal.4th 449, 502 ["Subsequent cases have limited the holding in Louis to its peculiar facts."].)