The evidence is overwhelming. The problem is, the evidence does not meet the burden of proof that a crime was committed. So the prosecution, with the apparent assistance of the judge, is attempting to convince the jury that they can convict based on the logical inferences that can be drawn from the evidence.
So wouldn't that make it "circumstantial" evidence, then?
The amount of testimony and papers presented was overwhelming, right up to the overwhelmingly long summation, all right. With a pile like that, he hopes the jury will glom onto SOMETHING nefarious enough to convict.
And he's probably right.