He might well have been according to a though-provoking study from the University of Rochester's James Brickley.

The study The Role of CEOs in Large Corporations:Evidence from Ken Lay at Enron can be viewed in two ways.

One is to see it as a total white-wash of someone who had been convicted of perpetrating a crime that is now synonymous with corporate fraud. On the other hand, it does provide some insights into how top executives spend their time, and whether they could be vulnerable.

Brickley bases his case around documents released through the Enron litigation. He finds that Lay performed a role at Enron consistent with existing economic theory and evidence, that he performed this role with reasonable diligence, and that while he was relatively well informed about Enron at a high level, it's unlikely that he would have had detailed information on many of Enron's more dubious transactions.

Lay, for example, met only four times with the chief financial officer Andy Fastow, who was responsible for many of those partnerships that brought about the company's collapse. By contrast, he met 29 times with president Jeff Skilling, and 35 times with his chief of staff.

Also, the records show Lay travelled extensively, meeting with with analysts, regulators, bankers, other CEOs, political leaders, employees, the media, customers, and others. He was at the Houston offices all day 33 percent of the time and part of the day 38 percent of the time. According to management literature, CEOs spend 25 to 50 per cent of their time on external issues.

His attendance at board meetings was 100 per cent but 90 per cent at audit committee meetings.

On the issue of whether Lay should have responded differently to whistleblower Sherron Watkins' anonymous letter, Brickley argues that Lay responded in a way that was in line with the common legal standard which is to consider whether the manager proceeded with the same care and diligence as would be expected of a "prudent person" in similar circumstances. Lay, he says, was flat out busy at the time because CEO Jeff Skilling had resigned. He also claims that the only reason Lay turned to law firm Vinson & Elkins to conduct a preliminary investigation was to have the whole thing proceed in a timely fashion. Doing anything else, Brickley says, would have stretched things out.

In the fallout from Enron and with Sarbanes-Oxley, CEOs now have to spend a lot of their time monitoring financial reports and internal controls. Brickley argues this imposes big opportunity costs on business. "While the gap between public opinion on the proper role of the CEO and actual CEO behavior may have narrowed in the post-Enron environment, value may have been destroyed."

Maybe, but the point remains that Lay was convicted by a court of law following an extensive trial. Had he behaved differently Enron might never have happened. And if other CEOs behave in a similar way, it's not like Enrons are popping up everywhere. So there are limitations to this study.

At the same time, however, it might serve as a reminder that some CEOs might not be that aware of what's going down.