China has released the dissident physician who became a national hero for exposing the government's coverup of the SARS epidemic, sending him home Monday night after 49 days of confinement aimed at pressuring him to disavow a letter in which he denounced the 1989 Tiananmen Square massacre.

Jiang Yanyong, 72, a semi-retired surgeon in the People's Liberation Army who had briefly become China's most famous political prisoner, was returned to his apartment in western Beijing about 11 p.m. and appeared in good health, his wife, Hua Zhongwei, said by telephone Tuesday.

She said she and her husband had been ordered by the Chinese military not to speak to reporters, and she declined to discuss the circumstances of his release. But asked how she felt, she laughed and said, "You can guess by how I sound."

A person close to the family said Jiang succeeded in resisting the demands of his jailers despite seven weeks of intense indoctrination sessions. The closest Jiang came to backing down was a statement in which he conceded that others might have used his Tiananmen letter for their own purposes, but he also wrote that he should not be held responsible for other people's actions, the person said.

Jiang's release represented a remarkable retreat by the most senior leaders of China's ruling Communist Party, who appeared to have ordered his detention and then backed down in the face of rising international and domestic criticism.

"He sounds good. He's in good spirits," said Jiang Rui, the doctor's daughter, who lives in California. She said that she had spoken to her father on the phone but that security officials were in the room with him and monitoring the conversation. She also said it was unclear whether he would be allowed to leave his apartment without permission or supervision.

"I'm happy he's home, but I don't know if he has any freedom at this point," she said. "I don't want to use the word 'free' yet. I would just say he's home. I tried to ask if he could move around freely, but it doesn't sound like it. It sounds to me like it's not over yet."

There was no comment Tuesday from the Chinese government. Jiang Yanyong was never charged with a crime, and the government had said only that the military was "helping and educating him" because he had violated military discipline.

Military officials have warned Jiang that his release does not mean his case is closed, a person close to the family said, but they have also indicated that he can resume giving medical advice to his patients. For his part, Jiang has expressed an interest in devoting his energies to China's AIDS crisis, the person said.

The decision to detain Jiang was a risky one because of the popular reputation for honesty and integrity he earned during the SARS coverup. In 2003, two weeks after a letter he wrote to China's state-controlled media blowing the whistle was leaked to foreign news media, the government fired the health minister and mayor of Beijing, sharply raised its official count of SARS cases and launched a campaign to alert the public of the disease and stop its spread.

Jiang then used the renown he had gained for another cause. In late February, he sent a letter to members of the Chinese leadership urging them to admit that the party's 1989 military assault on student-led, pro-democracy demonstrations in Tiananmen Square was wrong. The letter, in which he described treating scores of wounded civilians at his hospital on the night of the crackdown, was delivered to foreign media during the annual meeting of China's legislature.

While the party has acknowledged other errors, including the destructiveness of Mao Zedong's Cultural Revolution, it has refused to admit any mistake in its handling of the Tiananmen protests, in part because doing so might prompt new demands for democratic reform.

China's military chief and former president, Jiang Zemin, rose to power in the leadership purge that followed the Tiananmen crackdown, and a source familiar with the party's decision-making process said the nation's top military body, which he chairs, gave the order to detain the doctor. Jiang's successor as president and head of the Communist Party, Hu Jintao, serves as one of the vice chairmen of the body, the Central Military Commission.

Jiang Yanyong was detained on June 1, just days before the 15th anniversary of the massacre. Military and security officials seized him while he was on his way to the U.S. Embassy to apply for a visa to visit his daughter, then transported him in an armored vehicle to a remote military facility on the outskirts of Beijing, sources familiar with the situation said.

The officials threatened to keep Jiang in custody under 24-hour supervision until he "changed his thinking" about the Tiananmen crackdown and forced him to write "thought reports" every day as part of the indoctrination process, one source said.

But the doctor refused to budge. When Hua was allowed to visit her husband on June 30, he told her he had been writing the same statement every day for the past month and would not change his view of the massacre, a person close to the family said.

Then, on July 7, two officials with the military's General Logistics Department visited Hua and told her the investigation of her husband was nearing an end, sources close to the family said. The visit came two days after a report about Jiang's detention was published in The Washington Post and described on Phoenix Television, a Hong Kong station that enjoys close ties to Beijing and is available in many mainland offices and homes.

China's state-run media have not reported Jiang's detention, but word of his situation spread via the Internet, and hundreds of people have signed online petitions on his behalf. President Bush's national security adviser, Condoleezza Rice, pressed for Jiang's release in meetings with senior Chinese leaders this month.

During the July 7 visit with Hua, the military officials described Jiang as honest but politically naive, told her that he had finally made progress in his thought reports and showed her a statement in his handwriting, sources close to the family said.

But Jiang did not disavow his Tiananmen letter in the statement, the sources said. Instead, he acknowledged that other people might have used his letter for their own purposes, one person close to the family said. He also allowed that his jailers had helped him realize that the Chinese Communist Party in 1989 was "like a patient with complicated colorectal cancer" who faced imminent death unless emergency surgery was performed, the person said.

Jiang, a senior party member, wrote that surgery might prolong the patient's life, and he discussed the disease and the consequences of surgery in great detail in the statement. But he never said whether the patient -- in this case, the party -- should be saved, and he never condoned the military crackdown, the person said.

"It was a very calculated, measured statement," the person said. "He was very precise."

Jiang Yanyong was detained for denouncing the 1989 Tiananmen Square massacre.