Nobody is stopping any investigations against the bidens. The trial is against trump and his "perfect call", it has absolutely nothing to do with the bidens, they weren't on the call, just their names used. You don't call a witness to any trial that has no knowledge of the events, it's called relevance. Ironically it is trump and gop that has ignored the subpeonas, the actual witnesses to the call, like theys tryna hide something. Mr. Anonymous.
