CHICAGO (CNN) -- Former media tycoon Conrad Black, who was found guilty on Friday of mail fraud and obstruction of justice for his role in defrauding shareholders of Hollinger International and skimming $60 million from the newspaper conglomerate, will appeal the jury's verdict, Black's attorney Edward Greenspan said upon leaving the courthouse.
Black could face 15-1/2 to 20 years in prison, if the judge accepts the prosecutor's recommendation.
"We intend to appeal," said Greenspan. "We vehemently disagree with the government's position on sentencing. We believe based on the conviction of the charges here that the sentences for this type of offense are far less than what the government suggested."
At a later press conference, Patrick Fitzgerald, the lead U.S. Attorney prosecuting the case, suggested that 15-1/2 to 20 years could represent a "conservative estimate of the guidelines range," but added that a judge "will decide what the sentence is based on all the appropriate factors." Black could also pay up to $1 million in fines.
His associates Peter Atkinson, 60, of Oakville, Ontario, Jack Boultbee, 64, of Victoria, British Columbia, and Mark Kipnis, 59, of Northbrook, Illinois, were also found guilty on mail fraud charges. Each could serve up to 15 years in jail.
The court ruled that Boultbee and Atkinson will be allowed to return to Canada to serve their prison sentences.
After the verdict was announced, Fitzgerald described his reaction to the decision as "gratified."
"We think the verdict vindicates the serious public interest in making sure that when insiders in a corporation deal with money entrusted to them by the shareholders that they not break the law to benefit themselves instead of the shareholders," he said.
"The government wins, Black loses. End of story," said CNN Senior Legal Analyst Jeffrey Toobin.
On the 12th day of deliberations, the Chicago jury acquitted Black, 62, of Toronto, Ontario, of wire fraud, tax fraud and racketeering charges.
The guilty verdicts - on three counts of mail fraud and one count of obstructing justice - put Black's vast personal fortune at risk.
After appearing calm and collected entering the court, Black did not show any visible, emotional reaction once the verdicts were read.
Black has been restricted to the Chicago area and his passport has been handed over to the police until a sentencing hearing set for November 30 at 9 a.m. ET.
"Conrad Black will complete a remarkable fall from grace. He will certainly be sentenced to prison, perhaps for a considerable period of time," said Toobin.
Black did not testify in the trial.
Because he is British, he could serve his time in the United States or be transferred to a British prison.
The case was heard in the U.S. Illinois Northern District court.
During the trial, which began in March, U.S. federal prosecutors described the lavish, eccentric lifestyles of Lord Black and his wife, Lady Barbara Amiel, a journalist.
The case centered on an alleged corporate victim. Unlike the Enron case, this one resulted in no major loss of jobs, worker suffering or company collapse.
Nearly all the prosecution witnesses were granted immunity or allowed to plea bargain.
Black is "sort of [a] bad-boy celebrity," said George Tombs, who is writing his second biography about Black, to be published this fall. "This is somebody who's had tremendous power and he's lost it."
Legal troubles for Hollinger International and Black began in mid-2004, when the U.S. Securities and Exchange Commission published a report alleging "racketeering" and "corporate kleptocracy," which led to a $1.25 billion racketeering suit against Hollinger and Black.
That fall, after a U.S. federal judge threw out the racketeering suit, Black resigned as chairman and chief executive officer of Hollinger.
Months later, the SEC filed a civil fraud lawsuit against Black, Hollinger's former deputy chairman and chief operating officer, David Radler, and Hollinger.
"Black, Radler and other top executives didn't understand that investors had handed over their money in order to make more money, not to gain entree to a 'private gentleman's club,'" said Tombs, who added that the defendants "continued operating like they did in the '50s from the old Toronto days, wining, dining and schmoozing."
Federal prosecutors, under the guidance of Fitzgerald, said Black and the other three defendants defrauded shareholders of Hollinger International by collecting "non-compete" payments from the sales of media holdings.
In a non-compete, the seller agrees - in exchange for a payment - not to compete in the buyer's market. The prosecution argued that the payments ended up in the pockets of the defendants, as tax-free bonuses, instead of in the company coffers.
"Why were these men getting paid for non-competes that the buyer never requested?" asked Assistant U.S. Attorney Eric Sussman in his closing statement. "Why were they entitled to take this money and lie about it?"
The defense lawyers said shareholders and company directors had approved the payments.
The prosecution had originally hoped Radler would be their star witness. In exchange for a reduced jail sentence, Radler pleaded guilty in 2005 to fraud and agreed to cooperate with prosecutors.
But near the end of 25 hours of closing arguments, the prosecution changed course and instead labeled him as a "criminal" and "fraudster."
"You do not need to believe a single word David Radler told you to convict each and every one of these defendants," Sussman told the jury.
Tombs described Black as a modern-day Citizen Kane, a man who "had it all and lost it all."
In the early 1990s, Hollinger controlled 60 percent of Canadian newspapers in addition to hundreds of dailies worldwide, including the Chicago Sun-Times, the Montreal Gazette, Britain's Daily Telegraph and the Jerusalem Post.
Tombs said Black reveled in the pageantry of power. In 1999, the British government moved to make him a life peer of the British House of Lords, but Canada does not allow its citizens to carry the title. Black overcame that obstacle in 2001, when he renounced his Canadian citizenship and became Lord Black of Crossharbour, named for the London subway stop near The Daily Telegraph.
-- CNN's Maria Dugandzic and Nick McGurk contributed to this report 
