Led Zeppelin 2016

Led Zeppelin photographed circa 1970.

Chris Walter/Getty Images

A last minute move to keep Led Zeppelin's music expert from testifying could delay the trial that will determine if "Stairway to Heaven" copied a 1968 instrumental called "Taurus," which is set to begin Tuesday morning.

Attorneys seeking to prove Zeppelin infringed on songwriter Randy Wolfe's work claim when they deposed musicologist Lawrence Ferrara they discovered a massive conflict: he had been hired to evaluate the similarity once before.

"In 2013 he conducted a musicological analysis of the compositions of Taurus and Stairway to Heaven for Plaintiff’s publisher, Hollenbeck Music Co., a conflict that Dr. Ferrara and defense counsel knew about but purposefully failed to disclose," states a motion for sanctions filed Saturday. "Defense counsel misleadingly stated and implied that they had no knowledge about this situation, but in fact they orchestrated the entire scenario and have conspired with Plaintiff’s publisher (and fiduciary) since 2014 to undermine Plaintiff’s lawsuit, including by inducing the publisher to file false documentation with the Copyright Office in 2016 in an effort to undermine Plaintiff’s case."

Led Zeppelin Says 'Stairway to Heaven' Adversary Is Trying to Taint the Jury Pool

Wolfe's heirs sued in 2014, seeking not only monetary damages but also that he be credited as a writer on the iconic song.

Now attorney Francis Malofiy is not only claiming that his opposition conspired to destroy his case, but also that Ferrara can be bought.

“Ferrara is the go-to expert for major industry players,” states the motion. “He gives them the opinions they want. He has done so literally hundreds of times … Defense counsel wanted the expert they knew would give them the opinion they wanted, and went to great lengths to hide disqualifying information about him.”

Malofiy wants the court to preclude Ferrara from testifying at trial and to impose monetary sanctions on Zeppelin's attorneys for using a conflicted expert and trying to cover it up.

In light of this new information, Malofiy also filed a motion to ask U.S. District Court Judge R. Gary Klausner to reconsider an earlier motion that would reduce any damages by 50 percent because Wolfe’s songwriter agreement limited him to half of any recovery, so the trust would be limited in the same way. Malofiy argues that the publisher has violated its fiduciary duties by conspiring to defeat this lawsuit and "has rendered any applicable contracts, that could be used to reduce Plaintiff’s recovery by 50 percent, void and/or voidable."

Led Zeppelin Knocks Out Sound Recordings, Experts, More From 'Stairway to Heaven' Trial

The last round of exclusions weighed heavily in Zeppelin's favor. In April Klausner ruled that the jury won't hear any testimony about the wealth of Jimmy Page and Robert Plant, how bandmembers used drugs and alcohol and it won't actually hear the sound recordings at issue. The only music to the juror's ears will be recreations based on the original sheet music that was filed with the U.S. Copyright Office.

The trial has already been delayed once -- and the motions ask for it not to be delayed again -- so if Klausner doesn't need much time to mull over these filings, it could begin as planned Tuesday at 9 a.m.

This article was originally published by The Hollywood Reporter.