I can imagine why they would interview this Dr. several times. I'm sure they questioned if he had any enemies or conflicts with a neighbor or even a patient in the past. Perhaps he had a one time disagreement with a neighbor over a parking space and there has been some sort of contention between the two ever since. I believe the sk is obsessive-compulsive and has some animosity towards the doctor. I wasn't always sure that Shannon fell victim to the sk until it was revealed about the call from the doctor and the doctor stating that he didn't call. So now we are sure that the sk was in that neighborhood. Being that he is a former LE surgeon maybe an officer was injured in some way, was operated on and didn't fully recover after surgery and for whatever reason wasn't allowed back on the job. Maybe this individual was seeking to go out on disablity and needed the Doctor to state something specific so that he could collect money and the doctor refused, thus, the individual is no longer LE and not collecting monies he deems that he deserves.
There is a connection between the Doctor and the sk and it may be a very subtle connection--nothing that is quite noticeable or shouldn't be a mountain made out of a mole hill.
So in essence, it could be a former or current disgruntled EMS employee of which the doctor supervises, a neighbor who felt slighted by the doctor, or a former or current LE individual who wasn't able to go out on full disability and still works or quit or terminated still without any disability.
But, what do I know?