red john is NOT Walter Mashburn 

come on guys, lets really think about it. he is just another cover but he doesnt have any characteristics. People say that he is millionaire and has connections but that doesnt mean he is macabre, like Brett Partridge, or Ellis Mars, or Max winter, He just doesnt have that air of sociopath like Red John would be. i dont even think he is of any importance for the show, because if Bret Partridge is not Red John, at least i have the certainty that he is somehow connected to him, but Mashburn, probably doesnt even know RJ in person