In what is being called "a dramatic turn" in a protracted legal battle, documents publicized Monday reveal that the star witness in a case pitting rainforest villagers against a multinational oil giant has admitted to lying under oath in an effort to help Chevron avoid paying a $9.5 billion judgment for deliberate pollution of the Ecuadorian Amazon.

"Yes sir, I lied there...I wasn't being truthful," ex-judge Alberto Guerra reportedly told an international arbitration tribunal earlier this year when asked about his claim that the plaintiffs' legal team offered him a $300,000 bribe to ghostwrite the ruling in their favor.

Guerra's claim, VICE News explains, provided the underpinnings for New York federal judge Lewis Kaplan's 2014 ruling that the $9.5 billion verdict was obtained by way of fraud and coercion—a victory for Chevron, which had refused to abide by the judgement.

In fact, transcripts (pdf) of the 2015 tribunal proceedings made public on Monday—obtained through a disclosure request by Courthouse News with support from the Reporters Committee for Freedom of the Press—shine new light on the extent of Chevron's payments to Guerra for his false testimony, some $12,000 per month plus other perks which included a car, healthcare, and relocating him and his family to the United States.

"Chevron has now been busted by the lying testimony of its main witness," the plaintiffs' lawyer, Steven Donziger, told VICE. "The latest iteration of Guerra's testimony proves clearly that Chevron paid its star witness huge sums of money to present false evidence to frame the very people in Ecuador the company poisoned."

Amazon Watch, which campaigns to hold Chevron accountable for its toxic legacy in Ecuador, described the development as "a dramatic turn in the 22-year-old legal effort by Ecuadorian rainforest villagers to hold Chevron Corporation to account for massive on-going environmental contamination in the Amazon."

In a blog post on Monday, the non-profit's director of outreach and online strategy, Paul Paz y Miño, wrote:

Back in 2009, someone at Chevron was probably jumping up and down exclaiming "slam dunk". The company had found a key witness they could buy who was willing to say what they needed to pull together their fabricated fraud story in Ecuador. How did they "find" him? Easy, he came to Chevron asking for a bribe to help Chevron get out of its massive legal problems in Ecuador. That should have been a red flag, but fueled by their own arrogance and legal hubris Chevron moved forward with Guerra as their star witness. It turns out that rather than a Bond-esque spy thriller with intrigue and a sophisticated plot, the story for Chevron is more like "Harold and Kumar go to White Castle". Alberto Guerra, who we explained before is a corrupt ex-judge, claimed that the legal team for the Ecuadorians offered him a bribe to ghostwrite the judgment against Chevron. Guerra said he asked Chevron for a bribe first, and they turned him down, so then he went to the Ecuadorians. Despite the fact that Guerra was acknowledged by judge Kaplan himself to be less than credible, his testimony was allowed to stand (this is the same court that forbade evidence of actual contamination). The argument was that Guerra's testimony fit the "circumstantial evidence" against the Ecuadorian legal team. Except that evidence has also evaporated.

"This proves what we knew all along—that Chevron's RICO trial is a farce," Paz y Miño added in a press statement. "Guerra has so thoroughly perjured himself he should be behind bars. And so should Chevron management. Chevron has taken the people of Ecuador and the U.S. court system on a ride, full of lies, deliberate delay, and obstruction of justice. This is vindication for the Ecuadorians and counsel Steven Donziger and we now hope Chevron will finally do the right thing and clean up their toxic mess."

Donziger himself, who still works for the villagers, added that Guerra's latest testimony "demonstrates once and for all that Chevron's so-called racketeering case has completely fallen apart."

"Guerra has been the linchpin of Chevron's entire body of trumped up evidence," he said, "and he now stands not only as an admitted liar, but also as a shocking symbol of how Chevron's management has become so obsessed with evading its legal obligations in Ecuador that it is willing to risk presenting false evidence in court to try to frame adversary counsel and undermine the rule of law."

Amazon Watch is now calling for Chevron and its lawyers to be investigated and brought up on charges. "They have intimidated judges in Ecuador, bribed others, falsified evidence, and coached Guerra to submit false testimony in U.S. Federal Court and made a complete mockery of the our judicial system," Paz y Miño wrote.

"Chevron's polluted house of cards has come crashing down around them," he said.