What is the test for admitting identification evidence in a criminal case?

" 'In order to determine whether the admission of identification evidence violates a defendant's right to due process of law, we consider (1) whether the identification procedure was unduly suggestive and unnecessary, and, if so, (2) whether the identification itself was nevertheless reliable under the totality of the circumstances, taking into account such factors as the opportunity of the witness to view the suspect at the time of the offense, the witness's degree of attention at the time of the offense, the accuracy of his or her prior description of the suspect, the level of certainty demonstrated at the time of the identification, and the lapse of time between the offense and the identification.' [Citation.] 'We review deferentially the trial court's findings of historical fact, especially those that turn on credibility determinations, but we independently review the trial court's ruling regarding whether, under those facts, a pretrial identification procedure was unduly suggestive.' [Citation.] 'Only if the challenged identification procedure is unnecessarily suggestive is it necessary to determine the reliability of the resulting identification.' [Citation.]" (People v. Alexander (2010) 49 Cal.4th 846, 901-

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