Houston ? Imprisoned former Enron chief executive officer Jeffrey Skilling asked Friday 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 in 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 July 4, 2006, and his convictions were vacated.