Adelphia Communications Corp. founder John Rigas (search) and his son Timothy on Thursday were found guilty of conspiracy, bank fraud and securities fraud for looting the cable company and duping its investors.

Another Rigas son, Michael, was acquitted of conspiracy charges in the partial verdict; the jury was undecided on most of the remaining counts against him.

Former Adelphia Communications (search) Michael Mulcahey was found not guilty of conspiracy and securities fraud.

John Rigas, 79, and Timothy Rigas (search) were convicted of all 15 securities fraud charges against them and other counts. They each face 30 years in prison on the most serious charge, bank fraud.

The partial verdict came on the eighth day of deliberations following a three-month trial. Judge Leonard Sand asked the jury to return on Friday to resume deliberations.

"Ladies and gentlemen, you've been working very hard, and your task is not over," he said.

"This is a mixed verdict, and it demonstrates the difficulty in gaining convictions even when there appears to be overwhelming evidence of guilt," said Robert Mintz, a partner at McCarter & English LLP, in Newark, New Jersey. "Proof that executives lived the lavish lifestyle is not necessarily proof that they stole money from the company."

The case was tried in the same Manhattan federal courthouse that was home to other recent high-profile white-collar criminal trials, including those of domestic diva Martha Stewart and of banker Frank Quattrone.

A grim-looking John Rigas, who remained seated for half an hour after the verdict was read, had nothing to say to reporters as he left the courthouse with his lawyers. Timothy Rigas also had no comment.

Michael Levander, the lawyer for Michael Rigas, said, "It's a bittersweet day," as he left with his client.

Mark Mahoney, who represented Mulcahey, said the verdicts were "sort of bittersweet because of the condition of the others. But for (Mulcahey), I couldn't be happier."

John Rigas founded Adelphia when he bought a $300 license to wire Coudersport, Pa., where Adelphia was long based, for cable in 1952.

After taking the company public in 1986, Rigas began acquiring other cable systems, taking on a mountain of debt as he built Adelphia into the No. 5 cable TV operator.

Adelphia filed for Chapter 11 bankruptcy protection (search) in June 2002, soon after revealing that it was liable for $2.3 billion that the Rigas family had borrowed to buy company stock in a bid to retain control.

Prosecutors charged John Rigas with using the company treasury as his "personal ATM." For example, they said he used $26 million in Adelphia funds to buy timber land in front of his ranch because he did not want his view to be obstructed.

They also said Adelphia money was used to fund a golf course, country club memberships and vacations in Mexico, and that executives used corporate jets for personal travel. In one instance, they said, John Rigas flew a Christmas tree from Coudersport to Manhattan for his daughter.

Adelphia remains in Chapter 11, and under new management moved its headquarters to Greenwood Village, Colorado. The company was recently put up for sale, and many analysts have said it might fetch more than $20 billion.

Reuters and the Associated Press contributed to this report.