HOUSTON -- Former Enron CEO Jeffrey Skilling declared he's "absolutely innocent" on Monday as he began to testify in his own defense in his fraud and conspiracy trial.

Skilling, 52, said he "never -- not once" -- considered making a deal with prosecutors the way more than a dozen other Enron executives did. He said he will fight his charges "until the day I die."

Skilling addressed jurors directly, his eyebrows raised slightly, looking earnest and alert.

He acknowledged being nervous as his lawyer began his questioning. But he said, "I guess in some ways my life is on the line."

Skilling said he believed the Houston company was in good shape financially when he resigned from the company in August 2001.

The once-high-flying energy company collapsed into bankruptcy that December.

"It's almost inconceivable now what happened," Skilling said.

Although Skilling has faced harsh questioning from investigators before, this is the first time federal prosecutors who have pursued him for years will have an opportunity to grill him.

But the cross-examination likely won't come until midweek or later in Houston.

Skilling has awaited his turn to address jurors directly since the trial began more than two months ago. His testimony could well be the only difference between freedom and decades in prison -- depending on whether the eight-woman, four-man panel believes him.

Former federal prosecutor Robert Mintz said that for Skilling, the "testimony may be his only opportunity to save himself."

But if prosecutors can score some points during cross-examination, Mintz said Skilling "runs the risk of sealing his fate and almost guaranteeing his conviction."

Mintz said Skilling can expect cross-examination far more rigorous than softball questions he used to field from Wall Street analysts who adored Enron before it collapsed.

Mintz said Skilling will have to be able to handle these questions "without appearing arrogant or defensive."

Skilling and Enron founder Kenneth Lay are both on trial on federal fraud and conspiracy charges stemming from accounting methods in the months before its 2001 bankruptcy.

Lay is scheduled to testify later this month.

Skilling faces 28 counts of fraud, conspiracy, insider trading and lying to auditors for allegedly lying about Enron's financial strength.

Lay faces six counts of fraud and conspiracy for perpetuating the alleged scheme after Skilling resigned in August 2001.

They say they did nothing wrong.

If convicted, each could face decades in prison and millions of dollars in penalties.