Several years ago, David H. Brooks, the chief executive and chairman of a body-armor company enriched by United States military contracts, became fixated on the idea of a memory-erasing pill.

It was not just fanciful curiosity. A veterinarian who cared for his stable of racehorses said Mr. Brooks continually talked about the subject, pressing him repeatedly to supply the pill. According to Dr. Seth Fishman, the veterinarian, Mr. Brooks said he had a specific recipient in mind: Dawn Schlegel, the former chief financial officer of the company he led until 2006, DHB Industries.

There is no memory-erasing pill. And so Mr. Brooks sat and listened this year as Ms. Schlegel, her memory apparently intact and keen, spent 23 days testifying against him in a highly unusual trial in United States District Court on Long Island that has been highlighted by sweeping accusations of fraud, insider trading, and company-financed personal extravagance.

DHB, which specialized in making body armor used by the military in Iraq and Afghanistan, paid for more than $6 million in personal expenses on behalf of Mr. Brooks, covering items as expensive as luxury cars and as prosaic as party invitations, Ms. Schlegel testified.