Former Enron CEO Jeff Skilling

Former Enron CEO Jeff Skilling walks to the Bob Casey U.S. Courthouse for the second day of his testimony in his fraud and conspiracy trial on April 11 in Houston. (Getty Images/Dave Einsel)

A chronology of Enron Corp. and criminal cases emerging from its collapse:

1985 -- Houston Natural Gas merges with InterNorth to form Enron, HNG CEO Kenneth Lay becomes CEO of combined company the following year.

1989 -- Enron begins trading natural gas commodities.

1990 -- Lay hires Jeffrey Skilling to lead the company's effort to focus on commodities trading in the deregulated markets. Andrew S. Fastow is one of Skilling's first hires later that year.

1991 -- Richard Causey leaves Arthur Andersen LLP to join Enron as assistant controller.

1997 -- Skilling named president and chief operating officer of Enron. Fastow creates Chewco, a partnership, to buy the University of California pension fund's stake in another joint venture dubbed JEDI, but Chewco doesn't meet requirements to be kept off Enron's balance sheet. First step toward similar financial moves to hide debt and inflate profits that fuel Enron's downfall.

1998 -- Fastow named finance chief.

1999_ Causey named chief accounting officer. Fastow creates the first of two partnerships, LJM, purported to "buy" poorly performing Enron assets and hedge risky investments but really helps the company hide debt and inflate profits. Enron directors approve Fastow's plan that he run the partnerships that do deals with Enron while continuing as Enron's finance chief. Causey and former chief risk officer Rick Buy assigned to monitor such deals to protect Enron's interests.

August 2000 -- Enron shares reach high of $90.

December 2000 -- Enron announces that Skilling, then president and chief operating officer, will succeed Kenneth Lay as CEO in February 2001. Lay will remain as chairman. 2001:

Aug. 14 -- Skilling resigns; Lay named CEO again.

Aug. 22 -- Finance executive Sherron Watkins meets privately with Lay to discuss concerns of murky finance and accounting that could ruin the company.

Oct. 16 -- Enron announces $638 million in third-quarter losses and a $1.2 billion reduction in shareholder equity stemming from writeoffs related to failed broadband and water trading ventures as well as unwinding of so-called Raptors, or fragile entities backed by falling Enron stock created to hedge inflated asset values and keep hundreds of millions of dollars in debt off the energy company's books.

Oct. 19 -- Securities and Exchange Commission launches inquiry into Enron finances.

Oct. 22 -- Enron acknowledges SEC inquiry into a possible conflict of interest related to the company's dealings with Fastow's partnerships. Lay says, "We will cooperate fully with the SEC and look forward to the opportunity to put any concern about these transactions to rest."

Oct. 23 -- Lay professes confidence in Fastow to analysts.

Oct. 24 -- Fastow ousted.

Nov. 5 -- Enron treasurer Ben Glisan Jr. and in-house attorney Kristina Mordaunt fired for investing in Fastow-run partnership. Each invested $5,800 in 2001 and received a $1 million return a few weeks later.

Nov. 8 -- Enron files documents with SEC revising its financial statements for previous five years to account for $586 million in losses.