The Mentalist Season 5 is almost halfway through. The fictional CBI still doesn't know who Red John is, but we do know a couple of things about Patrick Jane's nemesis. How long would series creator Bruno Heller keep the viewers guessing?

The Mentalist Season 5: Is Patrick Jane Getting Closer to Red John?

Here are some of the most crucial Red John clues that have come up in the The Mentalist:

1. Based on available records, Red John started serial killing in 1998. He also uses the name Roy Tagliaferro.

2. The man Patrick Jane killed in the third season finale is not Red John. Jane acknowledged in the current season 5 that the faceless enemy he's been chasing after is someone he knows. This is after Red John's disciple Lorelei Martins revealed to Jane that he has, in fact, shaken the hands of the serial killer.

3. "Red John thinks of himself as a showman; an artist. He has a strong sense of theatre," Jane describes Red John's general profile.

4. In the episode where a little girl approached Jane to ask him if he has given up yet -- the girl said the man who told her to ask Jane was "white, wore a baseball cap, and had an odd voice."

5. Red John is "just under 6 feet tall; not muscular, but not soft either; short, straight hair; a gentle voice; rough, strong hands; he smelled of pine and nails and earth; and he liked to listen to me play the piano," said Rosalind Harker, the blind woman with romantic links to the serial killer.

'The Mentalist' Season 5 Episode 9: Ex-CBI Boss Virgil Minelli and [SPOILER] -- Their Red John Connection

"The Mentalist" viewers tweet the following while the latest episode is running in the U.S. via CBS:

"California Bureau of Investigation." "What the hell is that?" "We're like the FBI, only more conveniently located." #mentalist - Roxanne ‏@untiltheveryend

Love watching Patrick on the #mentalist - Tricia Duffield ‏@TriciaDuffield

The day Red John is discovered, I will be so thrilled for Jane. #TheMentalist - Adilah Makrup ‏@AdilahMakrup

Hopefully by the end of this season it'll be revealed who Red John is, they shouldn't really stretch it any longer. - ZV ‏@ZV28

Trying to find out who Red John is may be the most difficult thing ever.- Mike Doucette ‏@iDoucetteUps