HOUSTON — A former Enron Corp. executive's dramatic account of a confrontation over an alleged sham sale of three barges to Merrill Lynch & Co. was never documented or reported to her superiors, she testified Wednesday.

But Amanda Colpean said she was ordered by a colleague to lie about the transaction and manipulate documents so that the sale appeared to be legitimate — and Enron could satisfy its auditors. Ultimately, Colpean and 10 other Enron executives signed off on the paperwork.

Colpean was the first witness to testify in the conspiracy and fraud trial of four former Merrill executives and two former midlevel Enron executives accused of pushing through the deal in late December 1999.

Prosecutors say Enron wrongly booked a $12 million pretax profit from the deal because the energy company — specifically, former Enron finance chief Andrew Fastow — secretly promised that Merrill's interest in the barges would be repurchased within six months. A Fastow-run partnership bought the interest in late June 2000.

The government contends Enron needed the deal to appear to have met earnings targets, and the Merrill defendants participated in hopes of garnering more banking business from the energy company.

The defendants contend Enron was never obligated to buy back Merrill's interest in the barges and none of those on trial had final say on doing the deal.

In testimony Wednesday, Colpean said defendant Sheila Kahanek, a former in-house Enron accountant, came to her office and yelled at her for drafting a deal approval sheet that noted the buyback side deal. She said Kahanek ordered her to destroy all copies, because "putting certain information" in it would jeopardize the deal if the document was seen by outside auditors.

Colpean, who was above Kahanek in Enron's corporate hierarchy, said she refused to change the proposed document. But she acknowledged she later signed a copy that "didn't include all aspects of the deal" because it lacked language about a buyback.

She also acknowledged Wednesday she didn't document the confrontation or tell her superiors about it.

"I believe strongly that she would not have walked in my office acting as she did without my supervisor and her supervisor knowing what was going on," Colpean said.

The second witness to testify Wednesday, John Garrett, answered to Colpean at Enron and was a member of the barge deal team. He said that before Merrill surfaced as a buyer, the team tried in vain to negotiate with other buyers.

But those companies wanted a buyback guarantee given Enron's fervor to close the sale so quickly that they didn't have enough time to really study the purchase, Garrett said. He said Kahanek nixed buyback promises because "if we provide a guarantee, it's not a sale; it's a loan."

However, he said later that month Merrill emerged as a buyer and that deal included a six-month buyout schedule.

Garrett also testified that Colpean told him about the confrontation with Kahanek, and he took the buyback language out of the deal approval document at Colpean's request.

Defendant Dan Boyle, a former finance executive on Fastow's staff, also was among the 11 executives who signed the deal approval sheet.

In addition to Kahanek and Boyle, the defendants in the barge case are: Daniel Bayly, former chairman of investment banking for Merrill Lynch; Robert S. Furst, the former Enron relationship manager for Merrill Lynch, who answered to Bayly; James A. Brown, former head of Merrill Lynch's asset lease and finance group; and William Fuhs, former Merrill Lynch vice president who answered to Brown.