Third degree murder can be defined as homicide committed with the intention of causing bodily harm, but not necessarily death. It can be a killing that results from indifference or negligence or recklessness. Statutes defining third degree murder vary considerably from state to state. In California murders are classified into two- first degree and second degree.
Example of a State statute defining Third degree murder
Minn. Stat. § 609.195 MURDER IN THE THIRD DEGREE
(a) Whoever, without intent to effect the death of any person, causes the death of another by perpetrating an act eminently dangerous to others and evincing a depraved mind, without regard for human life, is guilty of murder in the third degree and may be sentenced to imprisonment for not more than 25 years.
(b) Whoever, without intent to cause death, proximately causes the death of a human being by, directly or indirectly, unlawfully selling, giving away, bartering, delivering, exchanging, distributing, or administering a controlled substance classified in schedule I or II, is guilty of murder in the third degree and may be sentenced to imprisonment for not more than 25 years or to payment of a fine of not more than $40,000, or both.