NEW YORK (CNN/Money) - The corruption trial of ex-Tyco CEO Dennis Kozlowski ended in a mistrial Friday after a juror thought to be holding out for acquittal received what was being called a coercive letter.

Judge declares a mistrial in Tyco case. CNNfn's Greg Clarkin reports. Play video (Real or Windows Media)

New York State Supreme Court Justice Michael Obus granted a defense motion for a mistrial after rejecting numerous earlier requests. Friday he cited what he said was outside pressure on one of the jurors. He did not give any details, but a person close to the case told CNNfn about the letter.

The source said that the judge met with the juror and the attorneys from both sides in his chambers Friday morning to discuss the letter and decided that a mistrial had to be granted. It is at least the second time this week that the judge met with the juror, who became the subject of intense media coverage after she appeared to flash an "ok" sign to the defense table last Friday. (See profiles of the jury members.)

The mistrial may have saved Kozlowski and co-defendant Mark Swartz, the company's ex-chief financial officer, from a guilty verdict, according to juror Peter McEntegart, a writer at Sports Illustrated magazine. Sports Illustrated is owned by Time Warner, which also owns CNN/Money.

"It's just so frustrating because we virtually had a verdict yesterday afternoon," he told CNN. "Someone said, 'Why don't we stay an extra half hour?' because we were that close."

McEntegart said he arrived at court on Friday thinking it would be a quick decision. "We thought it would be another ten -- well, nothing takes ten minutes in this trial, but half hour, hour," he said.

But the jury never got started on its 12th day of deliberations.

Notes from the jury room a week ago suggested that juror No. 4, a retired teacher and lawyer, was holding out for acquittal. A note from the jury suggested that she was not deliberating in good faith while a note from the juror complained the others would not allow for the possibility someone could have a good faith belief that the prosecution had not proved its case.

But McEntegart said that in the deliberations this week there had been a "turnaround" in the jury room.

After the juror believed to be the holdout flashed the apparent "OK" sign, the Wall Street Journal and New York Post took the unusual step of identifying her in news reports, which prompted the defense lawyers to file for a mistrial several times.

Juror Peter McEntegart

Obus, before dismissing the jury Friday, told them it is "simply a shame that this has to be done at this time."

The judge added that he was concerned "about the impact this may have on jury selection in the future."

Juror No. 4 sat with her arms crossed as Obus addressed the jury. Another female juror appeared to be in tears. The jury left the courthouse by bus without making any comments to the press.

"I've been doing this 40 years," said Swartz's attorney, Charles Stillman, after court proceedings ended. "If I piled up all my experiences top to bottom, I have not seen anything like this."

New York District Attorney Robert Morgenthau's office issued a statement saying the state would seek a retrial.

Related documents • N.Y. State v Kozlowski and Swartz Exec contracts • Dennis Kozlowski • Mark Swartz

Kozlowski and Swartz had been accused of bilking Tyco (TYC: Research, Estimates) of $600 million in one of the most closely watched of the recent corporate fraud cases.

They maintained their innocence throughout the trial. Swartz testified; Kozlowski did not take the stand.

Though it appeared the jury was headed for at least a partial guilty verdict, both Stephen Kaufman, a lawyer for Kozlowski, and Stillman said after court that they were disappointed the case didn't come to a conclusion.

Obus will meet with attorneys May 7 to discuss the date for a new trial, where the prosecution may hold the advantage.

"A mistrial is generally good for the defendant because he's gotten a look at the government's case," Frank Razzano, a former federal prosecutor, told CNNfn. "This case is going to be the exception to the rule."

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Prosecutors had been criticized by lawyers watching the trial for putting on too complex a case, which dragged on for six months.

Still, the mistrial is good news for the defendants, said David Berg, an attorney and author, given that the jury was apparently 11-to-1 for conviction.

"You cannot be disappointed when you walk out the front door and not into a holding cell," said Berg. "If Mr. Kaufman is disappointed, I am the tooth fairy."  

-- CNNfn's Greg Clarkin contributed to this report