Nobel laureate Ei-ichi Negishi’s wife Sumire Negishi, who was reportedly suffering from Parkinson’s disease, was found dead at a landfill in Illinois, United States, on Tuesday afternoon hours after the couple was reported missing, CNN reported.

A disoriented Ei-ichi Negishi, who teaches chemistry at Purdue University, was found walking nearby and was later hospitalised. The 82-year-old scientist won the Nobel Prize for Chemistry in 2010.

The couple were reportedly trying to get to an airport and somehow lost their way, the local NBC affiliate WTHR quoted an unidentified family member as saying. While the autopsy report is awaited, the county sheriff told the news channel that Ei-ichi Negishi is not a suspect in his wife’s death. The police also do not suspect any foul play.

“It appears that the Parkinson’s disease from which she has been suffering and the mental confusion that age can bring to the most brilliant minds combined to produce the recent tragic events,” Purdue University President Mitch Daniels said. “That these phenomena are so common does not make their consequences any less cruel.”

Negishi has been a researcher at the varsity for more than 30 years, and heads the Negishi-Brown Institute.