The voice on the phone left no doubt. "If you come by yourself," the man said, "we'll kill you."

Leonid Roshal was on the line with the guerrillas who had seized a school in southern Russia. He was asking if he could come inside to meet them, hear their demands and talk about a resolution to the standoff. The hostage-takers refused, Roshal recalled last week, unless he brought in three other men the captors had demanded as negotiators. But the others were not at the scene.

By many accounts, the Russian response to the school siege in Beslan this month was plagued by disorganization, crossed signals and the absence of key officials. As gunmen wired School No. 1 with homemade bombs and threatened to kill 1,200 students, parents and teachers they were holding, Russian authorities desperately searched for a strategy, but couldn't settle on one. For much of the siege it was left to Roshal, a Moscow pediatrician, to mediate the standoff on the telephone.

None of this was covered during Roshal's studies in Soviet medical school, but the physician had already done quite a few things he wasn't trained for. For the last quarter-century, he has rushed to the scenes of earthquakes, wars, revolutions, terrorist attacks, explosions, a railroad crash and a building collapse.

"I'm not afraid of anything in my life," Roshal, 71, said in an interview at his Moscow institute. "I'm not a young person -- on the contrary, even though they think that I'm strong. But I love to do my job. If I think that I'm needed, I'll do that."

"I didn't choose this role," he said. "I'm a doctor."

He certainly looks that part, with his white coat, gray hair and glasses that hang off the end of his nose. Not particularly tall, he nonetheless dominates a room with a crusty, self-assured manner. Well past the usual retirement age in Russia, he shows no signs of easing up, jetting off to Paris and Los Angeles, while keeping a small bedroom off his Moscow office.

Along the way, Roshal has become one of the most famous people in Russia. His celebrity went international in 2002 when he walked into a Moscow theater where Chechen guerrillas were holding nearly 900 people hostage. He offered medical care and tried to negotiate a peaceful end to the standoff. His efforts failed and 129 hostages were killed by a mysterious knockout gas that Russian commandos pumped through the ventilation system before storming the building.

Yet for all his courage, Roshal remains a figure of some ambiguity. No one publicly doubts his valor in dangerous situations or his commitment to children, yet privately some skeptics view him with suspicion as a man close to the government and point out that he appears to enjoy the limelight. Some of the Beslan hostages later reported hearing the guerrillas mock Roshal and denying they had asked for him.

He has spent time caring for children in Chechnya and was an early critic of the 1994-96 war there. But now, five years into the second war in Chechnya, Roshal has defended the state's handling of terrorist attacks such as the Moscow theater siege as well as the Kremlin's attempts to settle the Chechen conflict by installing loyal leaders ratified through disputed elections. The only picture on his office wall shows him with President Vladimir Putin.

Roshal acknowledged that Chechen guerrillas may view him with mistrust. "I don't know if they invited me as a person who's honest and would always speak the truth or they were not satisfied with my work in 'Nord-Ost,' " he said, referring to the play being staged when the Moscow theater was seized. "Maybe they wanted to kill me."

Roshal recalled hearing about the Beslan school seizure the morning of Sept. 1 from a reporter who he said told him the gunmen were demanding that he come. After speaking with Kremlin officials, Roshal was off within hours on a plane provided by Putin's office.

When he arrived at the crisis headquarters set up in Beslan, he found none of the three other negotiators demanded by the hostage-takers: Aslanbek Aslakhanov, a former parliament member from Chechnya who took a job as an adviser to Putin last year; Murat Zyazikov, a former KGB general who is now president of the nearby Russian republic of Ingushetia; and Alexander Dzasokhov, the president of North Ossetia, the province where Beslan is located.

Roshal said authorities gave him a mobile telephone number to call the people inside and used him as a go-between. "The first request was, 'Just let the women and children go,' " he recalled. "Then, 'Let us bring drugs and medicine. Let us provide necessary aid'; then, 'Provide water for the hostages.' And then, 'What are your demands?' "

The captors refused to deal with him until the three officials arrived. Roshal tried to enter the school alone, he recounted, but they would not let him, so he continued to talk with the hostage-takers on the phone, about 10 times a day.

"The important thing was to keep communication with them constantly," he said. "They were afraid their plan wouldn't work. They repeated several times: If someone turns off the phone, they would start killing hostages. 'If someone turns off the electricity, we'll start killing hostages.' One time they called me and said they saw soldiers moving around the garage near the school and if they saw more soldiers moving around they would start killing people. I reported it and that stopped."

All of Roshal's conversations were with one man who spoke Russian with an accent from the Caucasus region. Throughout the siege, the band of guerrillas refused to allow food or water to be brought in, much less medical aid. "These guys were much crueler than the guys in Nord-Ost," he said.

At one point, Roshal said, he confronted his interlocutor for targeting children. "I kept telling him, 'These are kids,' " he recalled. "He said, 'I'm from the mountains.' Usually, the idea is if you're from the mountains, you're very honorable. I told him, 'You're not a mountain man if you seized women and children.' "

At another point, the hostage-takers put the school principal on the phone. "She told me the situation was very hard," Roshal recalled. "She said they were very mad that the TV was saying there were only 300 hostages. She said there were over 1,200 people. And the terrorist corrected her and said 1,020." Roshal said he did not know why officials were publicly using the lower number. "For us to hide the number of hostages made no sense," he said.

The guerrillas continued to refuse offers of food and water. "They said that all the hostages were on hunger strike. And I said, 'Even the breast-fed baby? Did he declare a hunger strike? Or a 7-year-old boy?' " The captors, he said, "told their hostages they should not drink the water because it had been poisoned."

The authorities finally tried to end the impasse by offering the hostage-takers money, drugs and safe passage out of the school, as well as freedom for 30 imprisoned compatriots, according to Russian officials. Roshal conveyed some of the offers.

"I told them, 'Leave. We'll give you a green corridor.' I said, 'If you're afraid you'd be killed, I'll go with you.' " But the guerrillas refused.

On the third day of the standoff, a bomb detonated in the school gymnasium, apparently by accident, setting off the confrontation in which more than 338 children and adults were killed and more than 700 injured.

Roshal then headed for the local hospital, where his other skills were needed.

Leonid Roshal, left, helped remove body of a hostage killed in siege of a Moscow theater by armed Chechens in October 2002. Roshal sought to negotiate with hostage-takers this month in Beslan, where hundreds of students, teachers and parents were killed.