I respectfully disagree. Just having watched Chris Huges' testimony, it seems clear they are grasping and have nothing to show there was tampering. Also, watching how the prosecution allowed so much hearsay evidence in and failed to object when he could on grounds of relevance, the state is not afraid and just let the defense get on with it. The state had nothing to worry about.
Also, as to Chris Hughes, he seemed credible to me. I can imagine him calling a defense witness he knew, asking what it was about and warning them to be careful of a sleazy defense attorney. But, IMO, that's not witness tampering.