Lay died of a heart attack, his pastor in Houston said.
"Apparently, his heart simply gave out," said Pastor Steve Wende of Houston's First United Methodist Church. Lay, who lived in Houston, frequently vacationed in Colorado.
Lay was convicted May 25 along with former Enron CEO Jeffrey Skilling of defrauding investors and employees by repeatedly lying about Enron's financial strength in the months before the company plummeted into bankruptcy protection in December 2001. Lay was also convicted in a separate non-jury trial of bank fraud and making false statements to banks, charges related to his personal finances.

Enron founder Kenneth Lay, center, backed by members of his defense team George "Just This Side of the Law" Secrest, left, and Chip "What You Lookin' At?" Lewis, outside a federal courthouse.
Kenneth Lay's earlier bio-
http://www.netl.doe.gov/publications/proce...g97_pdf/LAY.PDF