First degree murder. A deliberate, premeditated killing is generally considered a first degree murder. Where the defendant planned the killing (as in a poisoning), she will usually be charged with first degree murder. The Los Angeles district attorney charged O. J. Simpson with two first degree murder counts in the deaths of his ex-wife Nicole Simpson and another person. The district attorney brought the first degree murder charges based on crime scene evidence, including a bloody glove, and on evidence that Simpson allegedly spied on his wife prior to the killings. Such evidence could have indicated a plan or premeditation to commit the crimes.
Second degree murder. In the widely-reported shooting death of Florida teen Trayvon Martin, the prosecutor in Seminole County, Florida, charged neighborhood watch volunteer George Zimmerman with second degree murder. The reason that the prosecutor charged Zimmerman with second degree murder is that Zimmerman shot Martin and there is no evidence that the killing was premeditated. To win a conviction of Zimmerman on the charge, the prosecutor will have to prove to the jury that Zimmerman intended to inflict grievous bodily harm on Martin.
Felony murder. Let’s assume by way of example that Bonnie and Clyde rob a bank. Clyde shoots and kills the guard during a confrontation. Clyde is charged with first degree murder and Bonnie is charged with felony murder because the guard died during Bonnie’s participation as an accomplice in committing the dangerous felony of armed robbery. Now let’s assume instead that Bonnie waits behind the wheel of the getaway car while Clyde robs the bank. After the robbery, Clyde jumps into the car and Bonnie speeds off, accidentally hitting and killing a pedestrian. Both Bonnie and Clyde are charged with felony murder, again because they accidentally killed the pedestrian while committing a dangerous felony.
Aggravating circumstances. Murder committed under certain circumstances, such as by laying in wait, or murder targeting a person in a particular position, such as a police officer, judge, or firefighter, can lead to a more severe sentence, including the death penalty.