The Times reports Richards had finished the Northwest Indiana Mudathlon when he went to a medical tent and complained he didn't feel well. He was taken to the hospital when his condition worsened.
Harris says there won't be an autopsy because Richards had a history of heart trouble.
Richards was a former editor and reporter for the Post-Tribune of Merrillville and Michigan City News-Dispatch.
The Mudathlon's website says it's a three-mile race through a muddy obstacle course. Similar races have been held in Kentucky and central Indiana and another is scheduled for Ohio.