Updated from 11:33 a.m. EDT

Former Enron executive Michael Kopper pled guilty Wednesday to criminal charges stemming from the government's investigation of the bankrupt energy merchant. In doing so, he becomes the first Enron official to admit to criminal actions while working for the company.

Kopper managed partnerships for Andrew Fastow, Enron's former financial chief, that were used to hide losses that eventually led to the company's bankruptcy. Kopper pled guilty to money laundering and fraud charges and agreed to surrender $12 million in assets. He will be released on a $5 million bond, and as part of his arrangement with prosecutors, he will cooperate with their investigation of Enron.

In securing a guilty plea from Kopper, 37, it's clear that prosecutors are aiming their sights at Fastow and possibly other high-ranking former Enron executives. Lawyers have described Kopper as being Fastow's right-hand man in running a number of off-balance sheet partnerhips with names like Chewco, Southampton and LJM2.

The Securities and Exchange Commission, in a civil complaint filed Wednesday against Kopper, charges that the former Enron executive and others at the company allegedly devised a scheme to use a series of off-balance sheet partnerships, or special purpose entities, to "defraud Enron's security holders by enriching themselves through the use of certain Enron SPEs."

The SEC contends that these SPEs should not have been treated as off-balance sheet entities under traditional accounting principles because they were controlled by Kopper, Fastow and others rather than truly independent third-party investors.

The commission also says these SPEs should have been included on Enron's balance sheet and that if they had been, Enron would have been shown to have a lot more debt and potentially failing assets on its books. In fact, Enron's collapse occurred last year, in part, because it was forced to restate earnings for several years and add billions of dollars of corporate debt back onto its books.

The SEC complaint and federal prosecutors, in bringing charges against Kopper, focused on three of these partnerships: Chewco, Southampton and a previously unknown entity called RADR.

Securities regulators detail a plan by Kopper and Fastow to use the three entities to personally enrich themselves, as well their family members and other Enron employees. In all, the complaint alleges that Kopper and Fastow generated nearly $30 million from the partnerships for themselves, their family members, other Enron workers and three bankers from National Westminster Bank, now part of the Royal Bank of Scotland.

The three NatWest bankers were charged by prosecutors last month for their part in the alleged scheme. Fastow isn't named as a defendant in the SEC complaint.

Kopper took over for Fastow as the managing partner of LJM2 last summer. But he was later forced out when a majority of the institutional investors in LJM2, including some big Wall Street firms, went to court early this year and got a Delaware state judge to strip Kopper of any role with the original $394 milllion partnership.

Earlier this month, Kopper refused to testify in a case he brought against the new managers of LJM2. The judge in the case ruled that without Kopper's testimony, the case couldn't continue, and the lawsuit was dismissed.