The death penalty does not work. Worse than that, it has resulted in the State killing innocent people and HUNDREDS of people on death row have been exonerated thanks to advances in tech that didn't exist at the time of their crimes (DNA for example).
http://www.innocenceproject.org/know/
When we are 100% certain of guilt we can use a permanent penalty. Until then the risk outweighs the gains.Especially when you factor in that there is ZERO deterrent value. Maniacs who eat their dead aren't exactly up on the current legal system's penal system or tremendous at forethought even if they know the penalties.
On the other hand, the prison system is an outright train-wreck. If the expense of this one guy getting a free meal bothers you... take a look at what we spend every year to keep non-violent pot dealers behind bars. The scale of that problem dwarfs the cost of warehousing death row inmates by several orders of magnitude. Also, keep in mind that we are subsidizing the chicken industry, scammy prepaid calling card companies and a huge for-profit leeching system with tax dollars to make this all happen.