Replacing a Juror who betrays bias or a fixed prejudgment of the issues: People v. Keenan (1988) 46 Cal. 3d 478, 532, 250 Cal. Rptr. 550, 758 P.2d 1081 ("A sitting juror's actual bias, which would have supported a challenge for cause, renders him 'unable to perform his duty' and thus subject to discharge. . . ."); People v. Thomas (1990) 218 Cal. App. 3d 1477, 1484-1485, 267 Cal. Rptr. 865 (court properly discharged juror who categorically refused to credit police officers; "A juror's duty is to weigh the evidence and credibility of witnesses with impartiality and to reach a fair and unbiased verdict.); People v. Feagin (1995) 34 Cal. App. 4th 1427, 1437 (trial court properly discharged juror who "had prejudged the credibility of the police officers . . . and was unable to cast aside her personal bias in weighing the evidence"); People v. Thomas, supra, 26 Cal. App. 4th 1328, 1333 (trial court found juror had "made up his mind before he went in there"); People v. Green (1956) 47 Cal. 2d 209, 215-216, 302 P.2d 307 (juror's statement that she did not think she could be fair to prosecution furnished good cause for her removal), disapproved on other grounds in People v. Morse (1964) 60 Cal. 2d 631, 637, fn. 2, 648-649, 36 Cal. Rptr. 201, 388 P.2d 33; People v. Bradford, supra, 15 Cal. 4th 1229, 1351-1352 (failure to discharge jurors not shown to be error where, despite initial "emphatic" statements, jurors deliberated for 10 days without betraying any inability to perform their functions).