A light just came on in my head about why Kirkland asked Jason Lennon if he knew him.  Since he and is brother were twins, he was trying to find out if his brother was Red John.

This still doesn't explain why he killed him.  If he really wanted to know Red John's identity, Lennon was still the best source of information. 

I watched the "Red John" episode last night and am more comfortable with McAlister being Red John.  However, if the meaning of some of the clues aren't explained during the rest of the season, Bruno Heller's reputation will be vastly diminished in years to come.