My suspect is Brett Partridge. Why? I have a reason:

Your voice:

Look closely to the chapters in which the coroner appears, her voice sweet and methodical.
I am a technical audio recording, I used a program to reduce the noise of the masks used by Rj the last chapter of the second season, and his voice is like Brett.
In a experimeto contario decided to do, I took the audio of Brett and added the similar effect of the mask and the result would not be different from identical to the chapter.

Everyone knows that Rj is very smart and Bruno Heller may be playing tricks on everyone.

We will not know the conduct of the sixth season.

Regards to all fans and fissured in "The Mentalist".