Correct. The confusion is found in the fact that they serve executive functions (i.e., enforcement functions), yet do not operate under direct control of the executive/enforcement branch of government that was outlined in the Constitution. The simple fact that any FBI unit has ever been allowed to investigate any President without immediately getting fired should tell you that. Congress has that power to launch investigations into Presidents of their own accord. Seeing the FBI do it to Trump should have made us all laugh, but because they really are a fourth branch of government under Chevron, we all just had to sit there, as did Trump, and watch it happen.