What is the test for a jury to convict a defendant of first-degree murder?

Beginning with "the presumption that an unjustified murder of a human being constitutes murder of the second, rather than the first, degree" ( People v. Anderson, supra, 70 Cal.2d 15, 25, 73 Cal.Rptr. 550, 447 P.2d 942), the court established an approach to evaluating the three types of evidence indicative of first degree murder: "The type of evidence which this court has found sufficient to sustain a finding of premeditation and deliberation falls into three basic categories: (1) facts about how and what defendant did prior to the actual killing which show that the defendant was engaged in activity directed toward, and explicable as intended to result in, the killingwhat may be characterized as 'planning' activity; (2) facts about the defendant's prior relationship and/or conduct with the victim from which the jury **115 could reasonably infer a 'motive' to kill the victim, which inference of motive, together with facts of type (1) or (3), would in turn support an inference that the killing was the result of 'a pre-existing reflection' and 'careful thought and weighing of considerations' rather than the 'mere unconsidered or rash impulse hastily executed' [citation]; (3) facts about the nature of the killing from which the jury could infer that the manner of killing was so particular and exacting that the defendant must have intentionally killed according to a 'preconceived design' to take his victim's life in a particular way for a 'reason' which the jury can reasonably infer from facts of type (1) or (2).

"... this court sustains verdicts of first degree murder typically when there is evidence of all three types and otherwise requires at least extremely strong evidence of (1) or evidence of (2) in conjunction with either (1) or (3)." ( People v. Anderson, supra, 70 Cal.2d 15, 26-27, 73 Cal.Rptr. 550, 447 P.2d 942.)