CNN/Money (NEW YORK) - A day after convicting two former top officials at Adelphia Communications Corp. and exonerating a third on charges of looting the bankrupt cable giant, a jury was still deadlocked on remaining charges against a fourth executive.

As a result, the trial judge declared a mistrial on the remaining charges against Michael Rigas, a son of Adelphia founder John Rigas and a former executive vice president of operations at the company.

Michael Rigas was found not guilty Thursday of committing wire fraud and conspiracy. But the jury could not reach a decision on 17 remaining felony charges against him.

His father and another brother, Timothy Rigas, were convicted Thursday afternoon on most counts against them.

The federal jury cleared Michael Mulcahey, Adelphia's ex-director of internal financial reporting, of any wrongdoing in the collapse of Adelphia, one of the country's largest cable operators.

The father and two sons were accused of concealing, with Mulcahey's help, $2.3 billion in loans and stealing more than $100 million from the now-bankrupt company. They were arrested two years ago and charged with 23 felony counts apiece. At the time, prosecutors called the case "one of the most elaborate and extensive frauds in United States history."

John Rigas, 79, founded Adelphia in 1952 and built it into the sixth-largest cable company before being ousted in an accounting scandal that came to light in 2002 amid a wave of government investigations into corporate chicanery.

During the 18-week trial that began in March, prosecutors sought to show that the Rigas family treated Adelphia like a "personal piggy bank" to pay for luxury condos and a golf course, and to cover personal investment losses. Government lawyers also charged that they lied about Adelphia's revenues and operations.

Defense lawyers insisted throughout the trial that their clients were innocent and had every intention of repaying the company for loans that defense lawyers argued were widely known about within the company.

John Rigas and his sons did not testify in their defense. The only defendant to take the stand was Mulcahey.

The jury deliberated for eight days before returning its guilty verdicts against John and Timothy Rigas and clearing Mulcahey, who broke down in tears upon hearing the jury's decision.

The judge declares a mistrial on the remaining charges against Adelphia's former executive vice president Michael Rigas. CNNfn's Allan Chernoff reports. Play video (Real or Windows Media)

Thursday ended with only Michael Rigas -- found not guilty of 6 charges -- unsure of his fate. John and Timothy Rigas face 20 to 25 years in prison.

Jurors returned to the Manhattan federal courtroom Friday morning to renew their deliberations on the remaining charges against Michael Rigas. They surprised the judge with a note before lunch, declaring they were deadlocked on the counts against Michael Rigas.

The judge urged them to keep trying, but after lunch Friday afternoon they told the judge once again that they could not reach a consensus.

Prosecutors now have the option of retrying Michael Rigas.

The trial's conclusion caps two days of triumphs for prosecutors intent on punishing corporate abuse in the executive suite.

Also Thursday, a federal judge overseeing an obstruction of justice case against Martha Stewart, the founder of the lifestyle media and retail company Martha Stewart Living Omnimedia (MSO: Research, Estimates) denied Stewart's second bid for a new trial. Stewart, who faces 10 to 16 months for lying during an insider trading investigation of her, is due to be sentenced July 18.

Another victory for prosecutors came earlier in the day when Kenneth Lay, the former chairman and CEO of Enron Corp. was indicted on 11 felony counts related to the Houston energy giant's late 2001 bankruptcy. Enron's fall touched off a series of corporate scandals at some of the country's largest companies, including Adelphia, WorldCom, Global Crossing and Tyco International.

"There certainly existed a mindset in the late '90s by some that the corporate till was a personal entitlement," said Jacob Frenkel, a Washington, D.C. lawyer who was once a federal prosecutor and a Securities and Exchange Commission enforcement lawyer.

"These cases have significant policy implications," Frenkel added. "To see two senior executives facing prison terms representing the balance of their lives sends a very strong message," he said, referring to Thursday's conviction of John and Timothy Rigas.

As for Martha Stewart's obstruction of justice conviction, Frenkel said: "Any lawyer can go to their client now and say 'Martha Stewart' and that person knows it means you cannot lie to the government."