Lay, who died of an apparent heart attack in Aspen, Colo., Wednesday was convicted in May of fraud and conspiracy and faced sentencing this fall. Fines were widely expected to be part of the punishment.
"The death of Mr. Lay in all likelihood will render the government's hard-fought victory null," said Christopher Bebel, a former federal prosecutor based in New York and who specializes in securities fraud.
Lay's death, however, has no effect on the many civil lawsuits by the Securities and Exchange Commission and former investors and Enron employees, The New York Times reported Thursday. A number of those suits are targeting Lay's estate.