SPOILER

It has confirmed the participation of Jack Plotnick (Brett Partridge) in chapter 6x08
http://www.imdb.com/title/tt3196216/fullcredits?ref_=tt_cl_sm#cast

It is true that also appears Gale Bertram, but between Bertram and Partridge who is more likely to be Red John? Partridge Obviously, he is "dead" and appear in the chapter.