What is the definition of murder and what is the test for sufficiency?

"To determine sufficiency of the evidence, we must inquire whether a rational trier of fact could find defendant guilty beyond a reasonable doubt. In this process we must view the evidence in the light most favorable to the judgment and presume in favor of the judgment the existence of every fact the trier of fact could reasonably deduce from the evidence. To be sufficient, evidence of each of the essential elements of the crime must be substantial and we must resolve the question of sufficiency in light of the record as a whole. [Citations.]" (People v. Johnson (1993) 6 Cal.4th 1, 38.)

"Murder is the unlawful killing of a human being, or a fetus, with malice aforethought." (Pen. Code, 187, subd. (a).) Malice may be express or implied. Express malice requires a deliberate intention to kill unlawfully. (Pen. Code, 188.) Malice is implied "when no considerable provocation appears, or when the circumstances attending the killing show an abandoned and malignant heart." (Ibid.) Implied malice has both a physical and a mental component. The physical component requires an act dangerous to human life; the mental component requires defendant know his conduct endangers another, but acts with conscious disregard for life. (People v. Patterson (1989) 49 Cal.3d 615, 626.)