Updated

An Illinois man who described himself as "the best known atheist-activist in the Midwest" died in a plane crash last week, officials said Monday.

The McHenry County coroner said an autopsy Monday revealed that Robert I. Sherman, 63, of Poplar Grove, died from multiple crash injuries. Authorities said Sherman was piloting a small plane that crashed into a cornfield either Friday night or Saturday morning. The crash is under investigation.

Sherman was an outspoken atheist and critic of using state money for religious purposes and having religious displays in public spaces. He also hosted a radio show.

Legal challenges he filed included a 1989 lawsuit over an Illinois law requiring public school students to recite the Pledge of Allegiance. He said the words "under God" contained in the pledge were unconstitutional. In 2007, he and his daughter, Dawn, sued over a state law requiring schools to have a moment of silence. Sherman also took a case to the U.S. Supreme Court involving a 2008 state grant that went toward restoring an 11-story cross in southern Illinois known as the Bald Knob Cross of Peace.

Sherman was behind a 2002 federal lawsuit complaining that it was unconstitutional to read a prayer at a Sept. 11 memorial service hosted by Chicago's mayor. A federal judge ruled against him. In 2008, Sherman sued to stop then-Illinois Gov. Rod Blagojevich's plan to give a $1 million state grant to help Pilgrim Baptist Church, a historic landmark on Chicago's South Side that had been badly damaged by fire.

Sherman spent time in jail during the 1990s in domestic violence cases. He was sentenced him to 120 days in 1999 when he failed to complete counseling after being convicted of hitting his son.