Len Bias was a basketball player at the University of Maryland when he died of a cocaine overdose. After his death, "Len Bias Laws" were enacted. Simply put, these laws make people who illegally manufacture, distribute, or sell illegal drugs strictly liable for a death that results from the inhalation, injection, or ingestion of the drug they are associated with.
If a drug dealer sells an illegal substance to a person, that person takes the drug and then dies as a result of taking the drug, the dealer can be charged with murder. Obviously this is easier said than done because of the covert nature of the drug trade.
A good example is this, say you bought cocaine and shared it with your girlfriend, she ingested it and died. You could be charged with murder because you supplied her with the illegal substance.