Old Sparky . . . Works?

Interesting article in the AP about recent studies claiming that the death penalty in the United States . . . prevents murders?

Among the conclusions:

- Each execution deters an average of 18 murders, according to a 2003 nationwide study by professors at Emory University. (Other studies have estimated the deterred murders per execution at three, five and 14).

Just for good measure, there's some academic snippiness too (the phrase "second-tier journals" is used).