I think cbi RON is red john because :-
(1) Ron is very similar to red john.Like R ed -jh ON.
(2) He's always there ..behind every one doesn't speak.As bruno heller said we've already seen red john many times .
(3)Red john knows everything that happens in the cbi office. so maybe he works in the cbi office . And RJ has many times contacted jane in the cbi office but still he untraceable . AND nobody can hack into cbi servers from outside.
(4) look carefully (4x13) when RED john meets rosalind harker. he's sitting like jane and the way he's holding the tea cup ...just look at his hand he's wearing a RING , it's blurry but ron is also wearing same kind of ring.
