What is the test for establishing a defendant's guilt beyond a reasonable doubt?

" '[I]ntent . . . is rarely susceptible of direct proof and generally must be established by circumstantial evidence and the reasonable inferences to which it gives rise.' " (People v. Jaska (2011) 194 Cal.App.4th 971, 984.) " 'Although it is the jury's duty to acquit a defendant if it finds the circumstantial evidence susceptible of two reasonable interpretations, one of which suggests guilt and the other innocence, it is the jury, not the appellate court that must be convinced of the defendant's guilt beyond a reasonable doubt. [Citation.]' [Citation.] Where the circumstances reasonably justify the trier of fact's findings, a reviewing court's conclusion the circumstances might also reasonably be reconciled with a contrary finding does not warrant the judgment's reversal." (People v. Zamudio (2008) 43 Cal.4th 327, 357-358.)