I think there is a chance that Tommy Volker is red john. In "if it bleeds it leads" neither he nor Jane meet at all or shake hands, 2 episodes before we are told Red John and Jane shake hands, ruling out Volker in the minds of the viewer. Is it not possible if Jane never see's Volker the whole episode and now he is to reappear being in sundays episode being investigated by lisbon that Volker could be someone Jane met before the death of his family, a rick client perhaps and on seeing him Jane will realise he met him.

Volker matches all the criteria for Red John also, rich, powerful, white male, psychopath, voice

Listen to this http://www.youtube.com/watch?v=Y3ssfgsw5bw

The directors are not going to make it an on screen hand shake and i think Jane meeting and realising hes met him in the next few episode would be a great twist