NEW YORK/WASHINGTON (Reuters) – Martin Shkreli, the former drug executive who raised the price of a lifesaving medicine by 5,000 percent, is set to appear as a witness at a congressional hearing on Thursday but is unlikely to answer lawmakers’ questions about price spikes. Shkreli, 32, sparked outrage last year among patients, medical societies and Democratic presidential front-runner Hillary Clinton after his company Turing Pharmaceuticals raised the price of 62-year-old Daraprim to $750 a pill from $13.50. The U.S.