BOSTON (AP) — A former executive of Biopure Corp. has been sentenced to three years in prison for pretending he had terminal colon cancer to dodge a federal lawsuit filed by securities regulators. Howard Richman, a former vice president at the Cambridge, Mass.-based biotech company, pleaded guilty to an obstruction of justice charge in March. He was sentenced Monday in U.S. District Court. The 57-year-old Richman, of Pearland, Texas, admitted he had instructed his lawyers to tell a judge he was ill. Prosecutors said he was trying to wriggle out of the lawsuit and avoid a large civil fine. The Securities and Exchange Commission complaint accused Biopure, Richman and three other executives of misleading investors about the prospects of winning approval for a synthetic blood product.