Beyond a reasonable doubt? I don't think so.
http://mrzine.monthlyreview.org/gasper181105.html
Stan has always maintained that he did not commit the crimes for which he was convicted. The main evidence against Stan was the testimony of informants who claimed that he had confessed to them. All of these "witnesses" were facing serious felony charges and had strong motivations to make a deal with the police to reduce their own sentences. In fact, in its 2002 ruling, the Ninth Circuit admitted that these informants had "less-than-clean backgrounds and incentives to lie in order to obtain leniency from the state in either charging or sentencing."
Since the original trial, another prisoner has come forward to say that he witnessed one of the informants being given the file on Stan's case by members of the Sheriff's Department so that he could learn details about the murders.
None of the physical evidence found at the two crime scenes, including fingerprints and a boot print, matched Stan. A witness's description of a person seen leaving the scene of one of the crimes did not fit him either. A shotgun shell supposedly matched a weapon he had bought several years earlier, but that gun was in the possession of a couple that was also facing serious felony charges. After they claimed that Stan had confessed to them, the investigation against them was dropped.
Now that Stan finally has competent legal representation, his lawyers have reinvestigated the evidence used in the case and found that it is even less adequate than previously known. According to one expert, for instance, the ballistics analysis used to identify the shotgun shell was nothing more than "junk science." Stan's lawyers have filed a new appeal with the California Supreme Court, pointing out many holes in the case against him, and the police and prosecutorial misconduct that convicted him.