To me RJ is Bertram. Almost everything makes sense that away, except...

Rewatched s06e01 several times. 

- Did or did not RJ knew he was being tracked by his phone gps? 

a) If he didn't knew, then who did the anonymous call and why? Not RJ, why would he warn the CBI? If he didn't knew he was being tracked he couldn't be calling to lure Lisbon to Brett house, so why would he call to CBI? It doesn't make sense. 
So maybe Brett did it? Before he got killed?  Maybe he was going to meet with RJ or another tyger tyger member at that house, and got scared. He was very upset with the way PJ looked on him, at the begining of the episode, maybe he talked about it with someone from tyger tyger or even RJ, and he became a target because of that..

 b ) But if RJ knew he was being tracked, then the anonymous call was probably made by him to lure Lisbon to him. But then, Bertram doesn't fit. Because if he knew he was being tracked, why on earth he leaved the phone so close to the house Brett was. He was more close then everyone else and the phone was stopped. It was a stupid thing to do.. I can't figure it out...