Here are a few articles of interest on the deterrence front. Charles Keckler of George Mason U. has this article in the Journal of Law, Economics & Policy on the question of which kinds of potential murderers are most likely to be deterred. He suggests targeting sentencing accordingly. However, it is important to keep in mind that deterrence is not the sole purpose, and imposing the greatest punishment on those most deserving of punishment is also important. The JLEP is not a peer-reviewed journal and therefore this article does not qualify for our deterrence abstract list, but it's worth noting. Update: See correction here.
Fred Thompson has this article in Town Hall.
John Lott has this article at FoxNews.com. He takes issue with the objection that the chance of being executed is so small that no one is likely to consider it, noting that in other situations people do change their behavior in response to very remote risks of death. It is also worth noting that the percentage probability of execution need not be to the right of the decimal point. The State of Delaware executed 1.5% of murderers in the period from restoration of capital punishment through 2004.