Baghdad, Iraq ? Hostage American reporter Jill Carroll appeared in a silent 20-second video aired Tuesday by Al-Jazeera television, which said her abductors gave the United States 72 hours to free female prisoners in Iraq or she would be killed.

The tape showed the 28-year-old reporter sitting in front of a white background and speaking, but her voice could not be heard.

Al-Jazeera would not tell The Associated Press how it received the tape, but the station issued its own statement calling for Carroll’s release. An Al-Jazeera producer said no militant group’s name was attached to the message that was sent to the station with the silent tape on Tuesday.

However, a still photograph of Carroll from the videotape that later appeared on the Al-Jazeera Web site carried a logo in the bottom right corner that read “The Revenge Brigade.” The group was not known from previous claims of responsibility.

Carroll was a freelance reporter for The Christian Science Monitor, and the newspaper released a statement from her family pleading with her captors to set her free.

The State Department responded to the videotape with a statement that U.S. officials were doing everything possible to win Carroll’s freedom.

“We continue to make every effort we can, working with Iraqis and others, to see Miss Carroll is returned safe and sound,” spokesman Sean McCormack said.

Carroll was kidnapped Jan. 7 in one of Baghdad’s most dangerous neighborhoods.

Also Tuesday, a court official said a Shiite lawyer is expected to take charge of Saddam Hussein’s trial, replacing the Kurdish chief judge who resigned.

Said al-Hamash, the second-ranking member of the five-judge tribunal trying the former Iraqi leader and seven co-defendants, is expected to replace chief judge Rizgar Mohammed Amin, said Raid Juhi, the top investigating judge who prepared the case against Saddam.