A federal jury on Thursday began weighing claims that Kevin Costner and his business partner cheated fellow actor Stephen Baldwin and a friend out of millions of dollars from a BP contract for using oil cleanup devices in the aftermath of the 2010 Gulf of Mexico spill.

A lawyer for Baldwin and his friend, Spyridon Contogouris, asked the eight-member jury to award the plaintiffs more than $17 million in damages. That's how much they estimate they would have received if they hadn't sold their shares in a company that marketed oil-separating centrifuges to BP before the oil giant made an $18 million deposit on a $52 million order for 32 of the devices.

Plaintiffs' attorney James Cobb told jurors they probably see the case as a "bunch of rich people fighting over money I'll never, ever see." Cobb, however, said his clients deserve to be compensated for being lied to by Costner and business partner Patrick Smith and defrauded out of their fair share of the BP money.

"I had no idea the spider's web of deception could be so pervasive and so hard to unravel," Cobb said during the trial's closing arguments Thursday.

Contogouris and Baldwin sold their shares in Ocean Therapy Solutions for $1.4 million and $500,000, respectively. Baldwin testified Monday he would have held out for much more if he had known BP had committed to ordering 32 centrifuges.

Attorneys for Costner and Smith said Baldwin and Contogouris knew that BP was preparing to order the centrifuges when they sold their shares and walked away from the company rather than gamble for a more lucrative payout if BP signed a binding contract. At the time they sold their shares, BP only had signed a non-binding letter of intent, the defendants' attorneys said.

"Why would you sell if you thought that (deal) was a possibility?" asked Smith's attorney, Roy Cheatwood. "Because you might have some concerns about whether the deal was actually going to get done."

Wayne Lee, Costner's attorney, argued his client's fame is the only reason he was sued. The plaintiffs were mistaken when they thought Costner would "roll over and give in" under the threat of a lawsuit, Lee said.

"This lawsuit never should have been brought," Lee said. "Mr. Costner never should have been a party to these proceedings."

Cobb said a series of text messages and emails show that Smith and Costner knew the BP deal was done before Baldwin and Contogouris sold their shares.

Jurors heard eight days of testimony before they began deliberating. Costner and Baldwin were ordered by U.S. District Judge Martin Feldman to attend each day of the trial, which they heeded. The judge thanked them at the end of the trial.

"I know that being here throughout the trial has been a great challenge for them," Feldman said.

Costner testified that he never saw Baldwin contribute anything to their company's efforts to persuade BP to use the centrifuges. Baldwin testified that no one asked him to invest any capital or lobby BP but said he used his celebrity to market and promote the centrifuges while he also worked on a documentary about the nation's worst offshore oil spill.

Costner had lost $20 million in an earlier effort to market the devices to the oil and gas industry, but Cobb said Costner and Smith each made $15 million off their investments in Ocean Therapy Solutions after the BP spill.

"OTS is an entirely new venture and entity, and he's not entitled to a credit for what happened in the past," Cobb said of Costner.

Jurors heard testimony that John Houghtaling, the company's CEO, had begged Baldwin and Contogouris not to sell their shares and promised them that a deal with BP was imminent.

"They didn't want to take a risk," Lee said. "(Contogouris) is the one who brought up the idea of selling. He set the price."

On Wednesday, a BP contractor testified that Baldwin had threatened to feed personal information about Costner to The New York Times if the two actors couldn't resolve their business dispute. Scott Smith, CEO of a company that sold about $1 million worth of oil-absorbing foam to BP after the spill, said he doesn't know if Baldwin followed through on the threat.

Cobb dismissed Smith's testimony as a diversionary tactic.

"They bring that to you, folks, because they've got nothing else," he said. "They don't have a legitimate defense, so let's throw some mud on the plaintiffs."

BP deployed a few of the centrifuges on a barge in June 2010. The company capped the well the following month, and it was permanently sealed in September 2010.