Hi there,
I was just thinking about the possibility of Red John's return;

One part of my belief that Red John will return was the titles of the episodes:
for all five forst seasons, most of the titles of the episode had "red" in their names, or a reference to the color (blood, strawberry, cherry, blush for example). 
As i'm french and i used to be looking to the episodes in french with a translation that did not include those references most of the time I did not pay attention to this before.

If you want to check, here is the list of the titles of the episodes from s1.
http://en.wikipedia.org/wiki/List_of_The_Mentalist_episodes


Since the "end" of red john, whiwh is supposed to be a fresh start for jane yet the titles of the episodes have kept references to colors in their names, every color except the red one, of course :

9-My Blue Heaven
10- Green Thumb
11- White Lines
12- The Golden Hammer
13-Black Helicopters
14-Grey Water 
15-White as the Driven Snow
16-Violets
17-Silver Wings of Time 
18-Forest Green 
19-Brown Eyed Girls
20- Il Tavolo Bianco (the white table)

I don't really know how to understand this but it can't be a coincidence or routine. We are all expecting the red name to appear in the last episode aren't we ?