CHICAGO (AP) — Conrad M. Black, once a media mogul whose newspaper empire spanned several continents, is headed back to prison after a federal judge ruled on Friday that he had not served enough time for defrauding investors.

Judge Amy J. St. Eve of United States District Court in Chicago, sentenced Mr. Black to three and a half years in prison after berating, then praising him. But prosecutors said he would be given credit for more than two years already served, meaning he will go back for little more than a year.

As Judge St. Eve announced the sentence with Mr. Black standing expressionless before her, his 70-year-old wife, Barbara Amiel, fainted on a wooden courtroom bench. As she sprawled across the laps of other spectators, medics rushed in to attend to her.

In a 20-minute statement before he was sentenced, Mr. Black, 66, spoke confidently and philosophically, citing poetry and maintaining he had been falsely accused. At no point did he apologize....