Let me draw a map:

William Blake:
Tiger, Tiger
Embrace of Partridge
The Great Red Dragon

The Great Red Dragon:
The Beast that comes up out of the sea.(on the wall in the house where partridge was "murdered" was 666, the mark of the beast)
In the Bible, the Red Dragon has seven heads (seven suspects) one of which is killed, only to be resurrected again.

The Mentalist Connections:
Embrace of Partridge: Brett Partridge
The Great Red Dragon: Title of episode seven, season six.
Tiger, Tiger: Poem recited by Red John which holds some significance. Written By WIlliam Blake, artist responsible for the two paintings mentioned before.

 
Brett Partridge is the first head that was slayed, in the end he will be resurrected.