What is the burden of proof in a death penalty case?

Defendants claims concerning the burden of proof are identical to those we considered and rejected in People v. Mendoza (2011) 52 Cal.4th 1056, 1096, 132 Cal.Rptr.3d 808, 263 P.3d 1 : " "The death penalty scheme is not unconstitutional because it fails to allocate the burden of proofor establish a standard of prooffor finding the existence of an aggravating factor." " "Nor was the trial court required to instruct the jury that there is no burden of proof at the penalty phase. [Citation.] The federal Constitution does not require that the state bear some burden of persuasion at the penalty phase, and the jury instructions were not deficient in failing to so provide." ( Ibid . )