Red John is Alex Jane,Patrick Jane's Father.

Red John is most likely a man
He is a white person as described by Haley
Red John has an average height: Rosalind described him as "just under 6 feet tall"
Red John has short straight hair (as described by Rosalind Harker)
Red John either has or puts on an odd, high pitched and soft voiceRed John should be older than 30 years (since his murders date back to the 90's)

Alex Jane is a man,white,can be under 6 feet tall and has odd voice.
Patrick Jane left him to start a new life with his wife. Why dont he kill Patrick when he taunted him on TV? The reason is because he is Patrick's father and he loves him. Like Bret Stiles say, Red John has a form of love with Patrick Jane. His dad must love him so much because Patrick is the only thing he has in his life. James Panzer, who is also known as San Joaquin Killer, get killed because he talk bad things about Red John. Why did he kill James Panzer and why he did not kill Patrick Jane? Why he kill Patrick Janes family instead? It is because Red John has some kind of obsession with Jane. He wants to keep Jane alive to play mind games with him.

The poem that Red John told Jane is The Tyger by William Blake from the Song of Experience. William Blake also wrote The Lamb from The Song of Innocence. What he is trying to say is that Patrick Jane is the lamb and he is the tiger. Alex Jane is the experience and Patrick Jane is the innocent.Red John is shown to be more smarter than Patrick Jane. Alex Jane teaches Patrick to be smart as he is now. He knows Patrick Jane more than anyone else. That is the reason why Red John is always one step ahead of Patrick Jane.

Sorry for my bad English,English is not my First Language.