CHICAGO, March 15 (Xinhua) -- The 2010 Nobel chemistry laureate Ei-ichi Negishi, reported missing by family members, has been found on a rural road in the state of Illinois, U.S. authorities confirmed.

However, his wife Sumire Negishi was pronounced dead in their car in a nearby area.

"An autopsy was performed and the cause of death is pending but foul play is not suspected," said a statement posted on the official blog of Ogle County sheriff's office, Illinois.

When Ei-ichi Negishi, a 82-year-old professor of organic chemistry at Purdue University in neighboring Indiana State, was first found on Tuesday, Illinois authorities did not realize he was the Japanese Nobel Laureate reported missing for days.

Ei-ichi was transported to a nearby hospital by first responders and investigators learned that Indiana police were looking for the couple, the Journal & Courier of Lafayette, Indiana, reported on Thursday.

The Negishi family released a statement on Wednesday, saying that the couple's car was stuck in a ditch near the road. The Nobel Laureate appeared to be searching for help and "was apparently suffering from an acute state of confusion and shock."

The family revealed that his wife Sumire Negishi, 80, was suffering Parkinson's.

Ogle County sheriff's office said Ei-ichi "is continuing to receive treatment in the Rockford hospital and this case remains under investigation."

Ei-ichi Negishi was awarded the Nobel Prize in chemistry in 2010 for his research on "palladium-catalyzed cross couplings in organic synthesis," which is also known as "Negishi coupling."