Former Enron Corp. CEO Jeffrey K. Skilling, who helped create the leading natural gas trading platform in the country before illegal schemes spiraled the company into bankruptcy and him to federal prison, is a free man.

The Bureau of Federal Prisons confirmed that Skilling, 65, was released from federal custody Thursday after spending 12 years in a minimum security prison in Alabama and six months at a halfway house.

The former front man for Houston-based Enron, Skilling joined the company in 1990 after leading McKinsey & Co.’s energy and chemical consulting practices. He was considered responsible for bringing Enron to the forefront in gas trading and its use of risk management products and forward contracting structures, using similar concepts in electricity, bandwidth, metals and other commodity products.

Skilling was president and CFO until early 2001, when he added CEO to his title. Kenneth Lay, who had formed Enron in 1985, remained chairman as rumors swelled he would be tapped as a member of President-Elect George W. Bush’s cabinet.

By the end of 2001, every dream that top executives and more important, investors, had put into Enron’s future collapsed into ruin, wiping out portfolios and retirement savings for thousands.

Only months into his tenure, Skilling resigned as CEO in August 2001 and Lay resumed running the company — just as federal investigators began to unearth a plethora of illegal schemes.

The company quickly spiraled downward and investors pulled back, and bankruptcy was declared before the end of the year in what at the time was the largest Chapter 11 filing in U.S. history.

The U.S. Securities and Exchange Commission began an investigation in 2001, followed In early 2002 by the Department of Justice. Along with other top executives, including Lay and former CFO Andrew Fastow, Skilling was indicted on fraud and conspiracy charges in February 2004.

Skilling was convicted in 2006 on 12 counts of securities fraud, five counts of making false statements to auditors, one count of insider trading and one count of conspiracy. He originally was sentenced to 24 years in prison and fined $45 million; the sentence was reduced six years ago.

Lay, 64, was convicted on 10 criminal counts for conspiracy, securities fraud, wire fraud and making false statements, but he died before sentencing of a heart attack.