Indeed, the only thing that should prevent his execution is evidence of innocence, unless it's evidence of misconduct at his trial. There is ample evidence of both:

Innocence: Main prosecution witness was a paid police informant who was supplied case information overnight before making his deposition. Bloody shoe print didn't match Tookie's. Fingerprints from scene didn't match Tookie's.

Misconduct at trial: Above evidence never introduced to "jury of peers," from which all possible black jurors had been removed (and there were only three in the total jury pool). Prosecutor had been admonished in past cases for racist comments. Moved Tookie's trial to a mostly white community, and in closing arguments compared Tookie to an animal at the San Diego zoo. Prosecutor removed black potential jurors from jury specifically because of their skin color.

As for his appeals being denied and all that, Chief Justice Robert's first case (Tookie's final appeal) was delayed while he was confirmed, then denied WITHOUT ANY COMMENT, which effifectively creates the precedent that openly racist prosecutors can remove potential jurors based on the color of their skin, and that racist comments in the courtroom are not grounds for retrial/appeal...

Having fun yet?
The man has been nominated for the Nobel prize not once, but NINE times.
See you at San Quentin: Midnight on December 13th (Monday night/Tuesday morning), come to San Quentin (Marin) to bear witness, to stand in protest, to stand in vigil, to listen and wait and watch while the state, with all its powers, forces a human being into a box and slowly (over eight minutes) kills him with chemicals. www.cwrl.utexas.edu/~tonya/spring/cap/frankie.htm

As for the death penalty's usefulness as a deterant, look up
www.deathpenaltyinfo.org/article.php
www.amnestyusa.org/abolish/deterrence.html

for more information on the death penalty:
teacher.deathpenaltyinfo.msu.edu/

Listen to the MP3 file above, a FRSC Interview with Barbara Becknell. There you'll find all the information that isn't in most of the mainstream discourse, and there you'll find the reason why indymedia is your media.