HOUSTON -- A possible agreement is being discussed that could reduce the prison sentence of former Enron Corp. CEO Jeffrey Skilling for his role in the collapse of the energy giant, according to the Justice Department.The possibility of a sentencing agreement was made public this week in a notice to victims of Enron's collapse."The Department of Justice is considering entering into a sentencing agreement with the defendant in this matter," the notice said. "Such a sentencing agreement could restrict the parties and the Court from recommending, arguing for, or imposing certain sentences or conditions of confinement. It could also restrict the parties from challenging certain issues on appeal, including the sentence ultimately imposed by the Court at a future sentencing hearing."The notice did not specify how an agreement might affect Skilling's sentence. Skilling, 59, the highest-ranking executive to be punished for Enron's downfall, has been in prison since December 2006.He is serving his term in a low-security facility outside Denver. Enron founder Kenneth Lay died of heart disease less than two months after trial.The Justice Department spokesman declined to comment, and Skilling's attorney did not return a phone call or email seeking comment.Convicted in 2006 on 19 counts of conspiracy, securities fraud, insider trading and lying to auditors, Skilling was sentenced to more than 24 years in prison. Houston-based Enron collapsed into bankruptcy in 2001 after years of illicit business deals and accounting tricks.Skilling's sentence was already in question. In 2009, an appeals court upheld his convictions but vacated his 24-year prison term and ordered that he be resentenced, saying a sentencing guideline was improperly applied, resulting in a longer term. He has yet to be resentenced.In 2010, the Supreme Court said one of his convictions was flawed and told a lower court to decide whether Skilling deserved a new trial. The lower court said no.Enron's collapse put more than 5,000 people out of work, wiped out over $2 billion in pensions and rendered worthless $60 billion in stock.