NEW YORK (CNN/Money) - Legal experts were divided Friday on whether Martha Stewart will win a new trial now that a key prosecution witness has been charged with lying on the stand.

Interim U.S. Attorney David Kelley comments on the charges of perjury against a key government witness and the possible impact on the convictions of Stewart and Bacanovic. Play video (Real or Windows Media) An expert who testified about the ink on a worksheet used by Martha Stewart's broker was charged with two counts of perjury. CNNfn's Mary Snow reports. Play video (Real or Windows Media)

Two former prosecutors and a defense attorney told CNN/Money that the government faces an uphill battle to convince a federal judge that the perjury indictment does not warrant a new trial for Stewart. "There's going to have to be a retrial," said Tai Park, a former federal prosecutor who practices at Shearman & Sterling in New York.

Indeed, lawyers for Martha Stewart and Peter Bacanovic indicated immediately after the perjury charges were announced that they would seek a retrial.

But two other attorneys said they weren't so sure the judge would be quick to order a new trial based on one piece in a pile of evidence against Stewart and her former broker, Peter Bacanovic.

The two-year-old Stewart saga took an unexpected turn Friday when David Kelley, the U.S. attorney in New York, announced that perjury charges had been filed against Secret Service lab director Larry Stewart, who testified in February about notations on a document related to the sale of Martha Stewart's ImClone Systems stock.

Stewart and Bacanovic were charged with conspiracy, making false statements and obstruction of justice during an insider trading investigation into her sale of stock in the biotech company in late 2001. The prosecution in that case argued that Bacanovic had altered a worksheet to look as if he and Martha Stewart had a pre-existing agreement to sell the stock when it fell to $60.

Secret Service lab director Larry Stewart

The perjury charges against Larry Stewart are related to his testimony that he participated in the original examination of Bacanovic's worksheet and the testing of the ink used to make the "@60" notation.

Martha Stewart and Bacanovic were convicted March 5 and Martha Stewart is scheduled to be sentenced next month. In light of Friday's developments, that June 17 hearing will likely be postponed while lawyers for Martha Stewart and Bacanovic ask for new trials.

An earlier request they made to overturn their verdicts based on alleged juror misconduct was denied in early May.

If the judge grants this latest bid and the government does not drop its pursuit, a new trial date will be set. If the judge denies the request, then Stewart and Bacanovic will likely file an appeal.

In announcing the new developments Friday, U.S. Attorney David Kelley said the evidence of Larry Stewart's misconduct would have "no impact" on the convictions of Stewart and Bacanovic.

When asked by CNN's Lou Dobbs what he thinks the likelihood of a retrial is, CNN senior legal analyst Jeffrey Toobin said: "I think it's in the realm of 50/50. This is a lot more significant than the juror issue." Toobin predicted that Stewart's June 17 sentencing date would "almost certainly" be postponed.

Other experts placed better odds on Stewart and Bacanovic winning a new trial.

To win their case, prosecutors had to show that Martha Stewart and Bacanovic intended to deceive investigators, and Larry Stewart's testimony was "absolutely critical" to their case, said Kevin Mahoney, a Cambridge, Mass. criminal defense lawyer who's written a Web log on the Martha Stewart case. "It was evidence that the government hammered most during the course of the case."

The decision whether to toss the convictions is up to the trial judge, Miriam Goldman Cedarbaum. She must now weigh how just significant Larry Stewart's testimony was in the jury's mind. It's a difficult analysis, legal experts said, because it's hard to know short of asking the jurors themselves.

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"If the judge, based on the evidence at trial, believes that this evidence was crucial evidence, [Stewart and Bacanovic] have a shot," said Stanley Twardy Jr., a former U.S. Attorney for Connecticut. "The government conceded," continued Twardy, "that it thinks a key witness didn't tell the truth. That's what's important here."

Even if Cedarbaum denies Martha Stewart's request, legal experts said the evidence of juror misconduct and now the perjury charges gives her a strong case on appeal. "This is a slow torture for the government," added Twardy. "The more the problems add up, at a certain point that will tip the balance" in Stewart and Bacanovic's favor.

Related Links • U.S. v. Stewart and Bacanovic • Disclosure Letter to Judge • Complaint (U.S. v. Larry Stewart) Related stories • Time to cut Martha loose? • Martha matches recalled • TV show suspended

But Jacob Zamansky, a New York securities litigator, predicted Stewart's request for a new trial would fail. "The ink testimony was only a bit of evidence related to the charges," said Zamansky. "With that falling there's still substantial evidence to support conviction."

Zamansky and John Wing, a former federal prosecutor, noted that Stewart's defense team faces one major hurdle in convincing Judge Cedarbaum that Larry Stewart's testimony swayed jurors' minds.

Bacanovic was acquitted on one count against him, falsifying documents by allegedly adding the 'at 60' note to sell Stewart's ImClone stock. By pointing to Bacanovic's acquittal on that charge, prosecutors could argue that the jury "had already discounted [Larry Stewart's] testimony," said Wing, who now practices at Weil Gotshal & Manges. "That could dampen the thrust of the defense's argument."