I thought it was that board of a-holes

Those DEA or whatever big wigs that were drilling them about the missing money, having them tailed etc. I thought they might have been behind the killings, I got the idea after the scene in wich they were being uncooperative to the detectives. It seemed logical , they were pissed that they stole the money, and after 6 months got nothing. I thought someone would have said something about how strange it was that that after 6 months of nothing they suddenly started to get killed off right after being reinstated.