The First Couple spent part of their weekend being grilled by Special Prosecutor Robert Fiske, who is investigating Whitewater. One focus of the interviews: any contact the White House had with regulators overseeing a probe into the alleged Savings and Loan scandal. Another area of concern was whether anyone tampered with evidence following the suicide of White House aide Vincent Foster. Just when Fiske will turn over his findings to Congress remains unclear, though the Clintons would probably prefer a release date as far from the 1996 election as possible. In the last comparable presidential inquiry, a subpoenaed former President Ronald Reagan testified about Iran-Contra figure Admiral John Poindexter--on videotape.