Last time they tried to execute him, the guy supposedly spent 3 or 4 hours alive "in excessive pain and torture" while they tried the "humane" stuff. Sounds like this worked much better. But somehow, this is now "veiled in secrecy" (and wth does that even mean?)
There is no excuse for not injecting lethal chemicals properly. Veterinarians euthanize large numbers of animals generally without incident.