Just going by memory here, but....

It seems a DA in the Houston area was working an AB case in south Texas or somewhere along the gulf coast. The first guy killed in Kaufman was assisting in some way the DA in the Houston area.

This would have let the AB become a suspect if someone started yelling 'AB, AB' like they did in Kaufman. It would have also provided a cover for the real shooter since the AB would have motive, more or less, and all the attention would be turned towards them and away from the true killer.

I am sure all of this will come out at the trial.