Not good enough. Eyewitness testimony has been shown over and over again to be unreliable. As a jurist, I could possibly send a man to prison on circumstantial evidence alone, just not to death.
Well, if you don't like circumstantial evidence, and you don't like eyewitness testimony, what WOULD cause you to condemn a man? Or are you just saying you oppose the use of the death penalty at all? Not taking any particular adversarial position on it myself, I just can't follow what you're thinking.