a) A person who kills an individual without lawful justification commits first degree murder if, in performing the acts which cause the death:
(1) he either intends to kill or do great bodily harm to that individual or another, or knows that such acts will cause death to that individual or another; or
(2) he knows that such acts create a strong probability of death or great bodily harm to that individual or another; or
(3) he is attempting or committing a forcible felony other than second degree murder.