Thought i'd just throw this out their, as a different perspective to those already offered. Bruno Heller has come out and said that Brett Partridge is dead. I believe Red John is a bit like Jekyll and Hyde, a psychopath that is excellent at hiding his bad deeds. The Jekyll side usually diminishes over time. In the case of Brett Partridge most people thought he could be red john from the very start. (Heller stated Red john was in it from the start, same as Brett Partridge). During the video read by Lorelei one of the lines was "I will start killing again". To do this Red John needs to regain control, Red John is aware of how close Patrick is to finding him, so he pretends to die. Therefore regaining the control his craves. This means killing his Jekyll (Brett Partridge) so all is left is his Hyde (Red John) for a final killing spree. Hence Bruno Heller saying Brett Partridge is dead, which throws off Patrick (or so Red John hopes).