Only about 10 claimed to see the crime. About 8 of those were too uncertain to stick with their original statements. The other 20 claimed to see him some other time that night and didn't see any crime directly.
Wiki says: In addition, three witnesses signed affidavits stating that Redd Coles had confessed to the murder to them.
Which is plenty to be "beyond reasonable doubt".
Wiki says: On August 30, 1991, after seven hours of deliberation, the jury recommended the death penalty and Davis was sentenced to death.
In criminal cases, after it is determined that a case will proceed to trial, a separate petit jury (formed of petit jurors) is then convened to hear the trial. In a few states and in death penalty cases, depending upon the law, a third jury or more often the same jury, will determine what the penalty should be or recommend what the penalty should be in the penalty phase. Usually, however, sentencing will be handled by the judge at a separate hearing. At a sentencing hearing, the burden of proof is now preponderance of the evidence, not proof beyond a reasonable doubt and hearsay is allowed. This practice gives the judge the power to change the finding of the jury when deciding on a sentence.[43]
Its usually the judge who decides what happens, to my knowledge, they just kind of pointed to the death penalty, which is, to my knowledge, something typically granted to someone who is convicted of murder, especially if they have other offenses (He allegedly pistol whipped a guy and shot an off duty cop, right?). I am pretty sure that is what the judge would have chosen without the suggestion.
