Good film. One question, did Silver

The first investigator suffered a heart attack while attending one of Silver's shows and the post-mortem concluded
the heart attack was the result of natural causes. Sigourney’s character is said to have a rare and long-standing vascular condition which could be the cause of her unexpected illness and sudden death.

It seems a bit of a coincidence that both deaths were related to heart diseases. I wouldn't have thought twice about it until the last part of the movie, when Silver/his assistant sends a guy to beat up Dr. Buckley in the bathroom. After seeing the lengths they were capable to go, I'm not sure anymore if Silver himself (or his team) wouldn't cause the death of anyone who would get too close to expose him as fraud. Silver makes clear that they keep track of their enemies (even having access to their medical records -Dr. Matheson's son condition-) so if they knew that someone had heart problems it could be easy to fake a natural death that wouldn't be detected in a post-mortem.