Barry Bonds’ trainer, Greg Anderson, told a federal judge in San Francisco on Tuesday that he refuses to testify in the baseball home-run champion’s perjury trial.

Anderson answered “No,” when U.S. District Judge Susan Illston asked, “Will you testify here today?”

Illston then found Anderson in contempt of court and ordered him into the custody of U.S. marshals, to be jailed for the duration of the trial. Anderson left the Federal Building courtroom escorted by marshals.

Anderson’s attorney, Mark Geragos, said he will appeal the custody order after Illston issues it in writing later today.

Prosecutors had sought to have Anderson as a key witness against Bonds, who is accused of lying when he told a federal grand jury in 2003 that he never received steroids or other performance-enhancing drugs from the trainer.

Anderson previously spent more than a year in jail for contempt of court for refusing to testify against Bonds before a grand jury investigating the alleged perjury.