 Poindexter was convicted on April 7, 1990, of five counts of lying to Congress and obstructing the Congressional committees investigating the Iran–Contra affair, which were investigating the Reagan Administration's covert arms sales to Iran and the diversion of proceeds to insurgents fighting to overthrow the Sandinista government in Nicaragua.The convictions were reversed in 1991 on appeal on the grounds that several witnesses against him had been influenced by his testimony before Congress, even though Congress had given him immunity for that testimony.From 1988 to 1989, Poindexter was senior scientist at Presearch, Inc., which had primarily been involved with defense studies and analysis.