How much does he get to keep after taxes and Attorney fees? :0)
ping
There are other costs to consider as well, such as providing ammunition to critics of the death penalty who wish to get rid of it entirely.
Expect these problems whenever someone is shielded from full responsibility for their actions. They had no disincentive against framing and convicting an innocent person. They personally suffer little cost. And, like the cowards they are, they chose someone, who because of his disability, was less able to defend himself.