As attorney general, Eric Holder has approved pursuing the death penalty in at least 34 criminal cases, upholding a long-ago pledge to Congress that he would vigorously enforce federal law even though he's not a proponent of capital punishment.

In the next day or two, Holder will make the most high-profile death penalty decision of his career in law enforcement: whether to seek capital punishment in the case of Dzhokhar Tsarnaev, the defendant in the Boston Marathon bombings. Three people were killed and 260 were injured in the bombing last April.

Massachusetts hasn't had a state death penalty law since 1984. History suggests it can be extremely difficult for federal prosecutors to win capital punishment cases in states that don't have a capital punishment law of their own.

(Associated Press)