A day after terrorists in Iraq issued a gruesome death threat to Manhattan journalist Micah Garen, Shiite rebel cleric Muqtada al-Sadr called on the kidnappers to release Mr. Garen.

Mr. Garen, a 36-year-old filmmaker, was abducted on August 13 with his translator, Amir Doushi, as they walked through a market in Nasiriyah. A group calling itself the Martyrs Brigade said it had abducted Mr. Garen and would execute him in 48 hours if their demands were not met. They demanded that American troops withdraw from the holy city of Najaf before the deadline.

Al Jazeera showed Mr. Garen kneeling in front of five masked and armed men from the Martyrs Brigade. Mr. Garen’s hooded captors brandished rifles and a rocket-propelled grenade launcher. Mr. Garen gazed silently at the ground throughout the video. The authenticity of the tape could not be verified.

Mr. Garen was working on a documentary about the looting of Iraqi antiquities. He has also worked as a freelance photographer for the Associated Press and his work has been featured in the U.S. News & World Report.

Though the south of Iraq is considered dangerous for foreigners, and another Western journalist had been kidnapped there last week, Mr. Garen told colleagues that he did not fear traveling there.

His abduction came as a shock to the journalists who live at the same hotel in Baghdad where he stayed for the past two months. The journalists immediately pooled their resources in an effort to secure Mr. Garen’s release. Every contact the journalists had with Mr. al-Sadr’s Mahdi Army was called in an attempt to pressure the Shiite cleric.

Mr. al-Sadr was at the center of negotiations with the Iraqi government yesterday about a truce and the disbanding and disarming of his Mahdi Army. This took place as the threat of an imminent massive attack by American and Iraqi forces hung over the heads of his Shiite rebels as they continued clashing with American forces in Najaf and Sadr City.

Days earlier, Mr. al-Sadr had ordered his supporters to free a British freelance journalist, James Brandon, in Basra. Kidnappers had threatened to kill the journalist for similar reasons.

Mr. Garen’s colleagues were implacable, frantically calling every al-Sadr-affiliated contact they knew in order to win Mr. Garen’s release. Their efforts initially brought only condemnation by high-ranking al-Sadr officials. But that was not enough. They needed Mr. al-Sadr.

“The problem is that they are in the middle of a war with the U.S. military and Iraqi troops,” said a Canadian photojournalist in Baghdad, Rita Leistner.

Ms. Leistner has spent the last four days acting as a liaison between New York and Baghdad relaying e-mails, phone calls, and contact numbers between the Committee to Protect Journalists, the State Department, Mr. Garen’s family, and the journalists working their contacts in the Mahdi Army.

Mr. Garen’s fiancee and partner in a film production company, Marie-Helene Carleton, was interviewed on Al-Jazeera calling for his release.

But the most important call – the one from Mr. al-Sadr – finally came through an aide last night.

“That’s the result of the work of the last four days by journalists based here,” said Ms. Leistner.

A top al-Sadr aide, Sheik Aws al-Khafaji, said Mr. al-Sadr’s militia was against kidnapping, “especially this journalist who rendered Nasiriyah great service.”

“We call upon the kidnappers to set him free and tried many times to contact many groups to help us find out about his condition,” Mr al-Khafaji said.