This is not a theory, but rather a ratification for one of the most confusing clues about Red John's identity - 'He is Mar', from episode "Red John's Friends", season 1.

I recently found a website that appears to have many TV show scripts - http://www.zen134237.zen.co.uk. It seemed weird to me that a random website could have access to that, but I looked for different scripts from different TV shows, and they're, without doubt, legit.

Anyway, back to Red John. Take a look at the script from Red John's Friends: http://www.zen134237.zen.co.uk/Mentalist/The_Mentalist_1x11_-_Red_John's_Friends.pdf

In Act 4 (final part), you'll find this:

Jared's finger still reaches out to the wall above the bath, where he's written, in blood - 'HE IS MA.'

This clarifies 2 things that, at least for me, were confusing and generated different theories and points of view:

1) It was Jared and not the Mexican hooker who wrote the message on the wall. I've read many fan theories that state Jared could have told the hooker what to write before he died. Some said that he could have told her to write the name 'Ellis Mars' (the psychic from Red Moon, also found in Jane's List of Suspects) on the wall (that sounds like 'Él es Mars' in Spanish, which means 'He is Mars'), which made him a primary suspect for this particular clue.

So, since Jared wrote it, it's definitely something we should look into, right? He was Tanner's cellmate and claimed to have info on RJ.

'I have dynamite information about Red John.  Enough to catch him.'

Did he, whoever, know who Red John was? Or did he know where to find him? 

If he actually knew who he was, then he'd most likely have written his name on the wall for the CBI to find him. He's not going to try to play games with them in his last seconds alive, is he?

If he didn't, then he probably wrote something about RJ that could describe him.

Lisbon: 'Jared was trying tell us something important.'

Many fans think that he wanted to write 'He is married'. That'd make sense, since RJ wears a ring in his left hand, as seen in season 4.

2) The script says that 'HE IS MA.' was what should be written on the wall. In the episode, though, there IS something next to 'Ma'. An r? An h?

What does it mean? I have no idea. But I really hope we do find out eventually.

Keep the theories coming!