Border czar Tom Homan didn't receive a normal background check for his role while his bribery probe was still ongoing:
Justice officials felt sure Homan would not be able to obtain a security clearance based on the evidence gathered. It remains unclear how Homan was eventually granted clearance.

Border czar Tom Homan didn’t receive normal background check during bribery probe
President-elect Trump initially balked at submitting names of likely nominees to the FBI for background checks, a basic step intended to flag possible financial conflicts or ethical problems.