I was asked to make a thread on this. Apparently Dr. Gilmer's sister was supposed to testify and went missing, although I can't find an article on that.
https://people.com/crime/after-a-bel...ystery-of-why/
After a Beloved Small-Town Doctor Murdered His Own Father, the Clinic's New Doc Solved the Mystery of Why
https://wlos.com/news/local/former-f...psych-hospital
Former Fletcher doctor who killed father wants transfer from psych hospital
https://www.thisamericanlife.org/492/transcript
Dr. Gilmer and Mr. Hyde