Well i've not really read much on this case so I don't have any strong views on it. Though from reading the OP it does seem pretty suspect and is probably another glowing example of the corruption and prejudice that most people (should) know exists in the american government.
However as far as the death sentence, i'm all for it in cases that are set in stone. For example, people who confess & gloat about their crime(s) and/or people who can 100% be convicted with substantial evidence. People such as Anders Behring Breivik.
Forget all the moral ****, putting criminals in prison for the rest of their life (and well in the UK a life sentence is only 20 years anyway) costs the tax payers more money. Not to mention they get access to xboxes, pool tables, sky tv etc (again i'm talking about UK prisons, not US, as that's where I live). I for one shouldn't have to pay for a criminal who took a life.
However using lethal injection in cases such as this with no real evidence can never be justified.