HOUSTON — Imprisoned former Enron chief executive Jeffrey Skilling yesterday asked for a new trial, saying the Justice Department used incorrect legal theories and "coercive and abusive tactics" to win a conviction, including threatening witnesses.

Skilling was sentenced last October to more than 24 years in prison for his role in the collapse of Enron Corp., once the nation's seventh-largest company. He was convicted along with company founder Kenneth Lay on May 25, 2006, on 19 counts of fraud, conspiracy, insider trading and lying to auditors.

Skilling reported to a federal prison in Minnesota in December. Lay died before his sentencing date.

Skilling is the highest-ranking executive to be punished for the accounting tricks and shady business deals that led to the loss of thousands of jobs, more than $60 billion in Enron stock value and more than $2 billion in employee pension plans after the company imploded in 2001.

"Profound, inherent weaknesses in the government's case — not just gaps in its evidentiary proof, but doubts about its basic theories of criminality — motivated the government to resort to novel and incorrect legal theories, demand truncated and unfair trial procedures, and use coercive and abusive tactics," Skilling's lead lawyer, Daniel Petrocelli, said in the appeal filed yesterday with the 5th U.S. Circuit Court of Appeals in New Orleans.

In the sharply worded, 237-page filing, Petrocelli portrays Skilling not as a villain but as someone who tried to save the company by offering to invest tens of millions of dollars — his entire net worth, effectively — to keep Enron operating "as panicking creditors and traders drained the company of cash in late 2001."

He says there was no tangible evidence Skilling engaged in criminal misconduct.

The appeal says while former chief financial officer Andrew Fastow's "secret thievery came publicly to personify the Enron story," the special team of investigators and prosecutors — appointed by President Bush to investigate the collapse — knew Skilling had nothing to do with Fastow's embezzlement.

At Lay and Skilling's trial, Fastow testified that his bosses were aware of fraudulent financial structures engineered by Fastow and his staff. Fastow, considered the mastermind behind financial schemes that doomed Enron, began serving six years in a federal prison in Louisiana late last year.

Given the facts, Petrocelli says in the filing, government prosecutors could indict and prosecute Skilling "only by cutting corners and bending the rules — and that is exactly what happened."

Justice Department representatives were not immediately available to comment.