SEATTLE—Rewards totaling $2.5 million are now being offered for information that helps solve the killing of federal prosecutor Thomas C. Wales in Seattle 20 years ago. Nicholas Brown, newly sworn in as the U.S. attorney for the Western District of Washington, announced Monday at a ceremony marking the anniversary of Wales’ death that the Justice Department had doubled its reward to $2 million, in addition to about $500,000 being offered by the National Association of Former U.S. Attorneys. Brown also said his office—long recused from the case—is taking on leadership of the investigation, as there are few remaining assistant U.S. attorneys in Seattle who worked with Wales. The investigation had been overseen by a special prosecutor in New York, Steve Clymer; transferring the oversight to Seattle will allow for fresh eyes and additional resources, Brown said. “Twenty years is far too long for this crime—this attack on the American justice …