I don't agree with the current law.
I believe you should be allowed to convict on circumstantial evidence within a reasonable doubt.
However, the death penalty must not be enacted without at least 2 eyewitnesses and/or hard physical evidence. I will settle for life imprisonment in those cases.
If they're not guilty enough to serve the sentence, they're not guilty. I don't think anyone should be convicted of a crime that the jury doesn't think they committed. Period.