"I wondered what Stephen Baldwin was doing," Costner said in his first direct mention of Baldwin since the trial began on Monday. "I never saw him do anything."

The federal lawsuit brought against Costner by Baldwin and business partner Spyridon C. Contogouris claims Costner cheated them by hiding details about the deal through which BP bought 32 oil and water separation devices developed by a company owned by Costner.

Both actors once invested in Ocean Therapy Solutions, the company that owned the oil-separating centrifuges.

BP made an $18 million advance payment for oil extraction devices to be used after the April 20, 2010, Deepwater Horizon disaster in the Gulf of Mexico.

According to the lawsuit, Baldwin and Contogouris claim they were not told about the deal with BP before they agreed to sell their shares in the company that had been set up to market Costner's extraction devices. As a result, they claim they were duped out of part of the $18 million deposit.

The plaintiffs want damages of $15 million to $20 million, according to Baldwin's attorney.

On Friday, Costner, dressed in a tan suit, at times seemed critical of himself. "Gosh I'm terrible," he said as he struggled to articulate the company's financial workings.

Costner's demeanor was calmer than it had been on Thursday, when he expressed concern about the case. "My name is at stake," Costner said.

The star of such movies as "Field of Dreams", "The Untouchables" and "The Bodyguard," Costner, 57, had a few heated exchanges on Thursday with the plaintiffs' attorney, James Cobb. At one point, Costner interrupted Cobb's questioning and said: "I'm finished with you being loud with me."

"Mr. Costner, we don't need incivility," U.S. District Judge Martin Feldman said. "This is not a wrestling match."

Baldwin, 46, has yet to testify. The youngest of four brothers all of whom are actors, he is known for roles in "The Usual Suspects" and "Flyboys."

(Editing by Chris Baltimore)

• A Permanent Economic Emergency