Oversight is supposed to be performed by Congress, the IGs, and superiors. Problem is most people are risk adverse and don't want to deal with wrongdoers because it commonly leads to blow back on oneself. The system needs to change to protect the honest folks.
All they have to do is cut some of DoJ's money. This can be approved at the committee level which Reps control.
At one time, I worked in a different agency and saw this happen to some co-workers. These people would not give Congress requested info. So, staffers zero'ed out their accounts and transferred all that money to ME. It was hilarious watching these idiots run around like chickens without their heads.