The former chief investigations counsel for the House Oversight Committee has been helping to prepare Bill Gates, the billionaire co-founder of Microsoft, to testify privately in the panel's Jeffrey Epstein investigation on Wednesday. Representative James R. Comer of Kentucky, the Republican chairman of the committee, formally requested in March that Mr. Gates appear before the committee for a transcribed interview. His request came after files released by the Justice Department showed that Mr. Gates met with Mr. Epstein, the convicted sex offender, multiple times and that his closest advisers were in frequent contact with the disgraced financier until 2019, the year of his death in prison. In preparing for the deposition, Mr. Gates has turned to Jake Greenberg, who until December was spearheading the oversight panel's Epstein inquiry in his role as the committee's top investigative official. Mr. Gates's close relationship with Mr. Epstein has roiled his foundation, which has authorized an outside review of its ties to Mr. Epstein. Representative Suhas Subramanyam, Democrat of Virginia, said in an interview that he wanted to know what Mr. Gates "knew of Epstein's crimes, and the nature and extent of their relationship." He added, "Epstein was known for befriending and even blackmailing rich and powerful men, and I want to know if Gates was one of them." Mr. Gates has sought out powerful inside players to help him weather the scrutiny. He hired John Moran, a former lawyer for the Justice Department, who helped him secure an agreement with the committee for him to appear off camera, The Wall Street Journal reported.