The sheppards were osteopaths. The Sheppard estate speaks of a conspiracy against Dr. Sam but its not a conspiracy of murder. The Sheppard estate says there was ill will between traditional physicians and the Sheppards who were well know osteopaths. The state contends that animosity is what fueled what then coroner Sam Gerber did. There had to be more than that, I think, and I'm still digging into this.
Witnesses are dead.
Evidence is degraded. One of the interesting things in watching the trial is that the few people with first hand accounts of things like the crime scene and investigation are now elderly. They came into court in wheelchairs and being helped by nurses and hearing aids. And it made it difficult for both sides to accuse them of being liars. These lawyers are whipper snappers by comparison and it was interesting to watch them struggle with how to accuse someone so much their senoir.