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

Murder is the unlawful killing of a human being or fetus with malice aforethought. (People v. Taylor (2004) 32 Cal.4th 863, 867.) Malice may be either express or implied. (Ibid.) It is implied when the killing results from an intentional act, the natural consequences of which are dangerous to life, which act was deliberately performed by a person who knows that his conduct endangers the life of another and who acts with conscious disregard for life. (Ibid.) Implied malice has both a physical and a mental componentthe physical component being the performance of an act, the natural consequences of which are dangerous to life, and the mental component being the requirement that the defendant knows that his conduct endangers the life of another and acts with a conscious disregard for life. (Id. at p. 868.)