How about his testimony? Even though nothing about 'police integrity' was mentioned in the EDTA test request, he talks about it in his testimony. And he assures that the blood didn't come from the vial for the samples he DID NOT even test. If that is not a proof of bias, I don't know what is.
[I never mentioned the hole in the vial in my comment. I looked in to it and found that it is absolutely possible that the vial has a hole in it. ]