This might be too nuanced for you. You've ignored the most important points in this discussion. However, to answer your question, it depends on the subject matter of his testimony. If he's testifying about specifics about the state of Stites' body, that might be a problem if someone who examined her body sooner after her death disagreed with his testimony, which isn't the case no matter how much you want it to be. If he's testifying about the science of agreed upon facts (for example, testifying how long sperm can stay in the vaginal cavity), then it wouldn't matter if he was testifying about the Cain and Abel murder.