In this case, where the scientific evidence raised reasonable doubts as to
defendant’s guilt, other means were advanced to persuade the jury: the unprecedented
use of the trial judge as a witness for the prosecution on a central point in the case; the use of inflammatory evidence of uncharged conduct, much of it decades old, which was
improperly argued as pure propensity evidence; and the castigation of appellant’s counsel
for purportedly having bought expert witnesses to make up “ridiculous testimony” in
order to hide the truth.
“It is too much the habit of prosecuting officers to assume beforehand that a defendant is guilty, and then expect to have the established rules of evidence twisted, and all the features of a fair trial distorted, in order to secure a conviction. If a defendant cannot be fairly convicted, he should not be convicted at all; and to hold otherwise would be to provide ways and means for the conviction of the innocent.”
(People v. Wells (1893) 100 Cal. 459, 465.)

Appellant was not fairly convicted. Reversal is required.