(a) A person commits the offense of murder when he unlawfully and with malice aforethought, either express or implied, causes the death of another human being.

(b) Express malice is that deliberate intention unlawfully to take the life of another human being which is manifested by external circumstances capable of proof. Malice shall be implied where no considerable provocation appears and where all the circumstances of the killing show an abandoned and malignant heart.

(c) A person also commits the offense of murder when, in the commission of a felony, he causes the death of another human being irrespective of malice.

(d) A person convicted of the offense of murder shall be punished by death or by imprisonment for life.