Ok this may look strange... but i noticed 2 things in the end of S6 E2 :

1) RJ is talking to patrick on the phone saying  : 

"Can I take a message? ..... .... No ?"
When he says the word "NO" on the phone, HIS BOTH HANDS ARE ON THE KNIFE ....... meaning the actual killer isn't the one talking on the phone...

2) then who's talking on the phone at this very moment ? I just noticed that Ron was going to make a call... and his voice sounds a little like RJ's .... and why would Heller put this "useless" character at such a decisive moment ?

What do you think ?