What is the duty of counsel to instruct on manslaughter in a criminal case?

The "duty to instruct on lesser included offenses . . . arises . . . regardless of the trial theories or tactics the defendant has actually pursued." (People v. Breverman, supra, 19 Cal.4th at p. 162; see also People v. Barton, supra, 12 Cal.4th at pp. 194-195; but see

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People v. Sinclair (1998) 64 Cal.App.4th 1012, 1019, 1020 [There is no "duty to instruct on lesser offenses when there is a complete denial of any complicity in the charged crime by the accused"; but a "defendant's . . . denial she or he committed a homicide may be colored by other testimony, which creates substantial evidence sufficient to support manslaughter instructions"].)