Enron's former chief executive Jeffrey Skilling has stepped down from the witness stand after almost eight days of grilling over the firm's collapse.
Mr Skilling is battling to clear his name
Mr Skilling is on trial in Houston accused of hiding problems at Enron that led to the energy company going bankrupt with debts of $31.8bn (£18bn).
He has denied the charges and claims the fraud was committed by others.
Kenneth Lay, the founder of Enron, also is facing fraud and conspiracy charges and is due to testify early next week.
Mr Skilling and Mr Lay face lengthy jail terms and analysts said the verdict may well be decided by their time on the stand.
"This is a case that turns on credibility," said Brian Wice, a Houston-based defence attorney who has been watching the court-room battle unfold.
Mr Skilling is charged with 28 counts of conspiracy and fraud related to the Enron's collapse.
His former boss Mr Lay faces six charges of fraud and conspiracy.
1985 - Enron formed
December 2000- Skilling becomes chief executive
August 2001 - Skilling quits
October 2001 - Enron reports $638m third quarter loss and $1.2bn fall in shareholder equity
October 2001 - Securities and Exchange Commission begins inquiry into firm
November 2001 - Enron shares sink to 10 year lows as buyout deal falls through and further losses are revealed at the firm
December 2001 - Enron files for Chapter 11 bankruptcy
2002 - Criminal investigation of Enron launched
2004 - Skilling and Lay charged over Enron collapse. Former finance chief Andrew Fastow pleads guilty to criminal charges and agrees a 10 year jail term
January 2006 - Enron trial begins
The men argue that while they may have headed the firm, the fraud and concealment of Enron's debts were carried out by lower-level employees such as former chief financial officer turned prosecution-witness Andrew Fastow.
They also contend that Enron was a healthy firm brought down by panic-selling from investors rather than serious accounting fraud.
Mr Skilling ended his time in the witness box by reiterating his innocence and denying charges that that he had failed to pay taxes.
"I feel that I've had fair opportunity to explain the questions about the company," Mr Skilling said outside the courtroom in Houston, adding that "you can never say everything you want to say".
Analysts said that Mr Skilling had a mixed time on the stand.
"Skilling did a good job on direct examination, but on cross examination, he was too argumentative and did not answer questions in a straightforward way," said Jacob Zamansky of New York law firm Zamansky and Associates.
Former federal prosecutor Michael Wynne said: "For him to be acquitted, the jury's got to buy his story and discount everybody else's."