A top official at the U.S. Justice Department was a law partner with Hunter Biden’s attorney Chris Clark, raising serious concerns about potential conflicts of interest as the years-long federal probe into the president’s son has reportedly reached a critical stage. Clark, a partner at New York-based firm Latham & Watkins, worked with Nicholas McQuaid on at least four different cases when he was also a partner at the practice, court records indicate. The cases were high-stakes commercial litigation where the pair regularly defended clients facing multimillion-dollar lawsuits. McQuaid was named acting head of the Justice Department’s criminal division on...