Critics have said that these people are victims of illicit renditions by increasingly bold Chinese security forces, and Ms. He said she believed that Mr. Li would have returned to China only under force or threats, despite his assertion that he came back freely.

“His tone was like they’d given him guidance,” Ms. He said. She said that her husband sounded calm, but that he had told her not to interrupt him with questions.

“I said to him, ‘Where are you? Just where are you? Tell me. At the very least, I have to find a lawyer for you,’ ” Ms. He said. “But the line was silent for a long time, and I knew someone at his side was telling him what to say, and he said, ‘Don’t get involved. Don’t ask so much. I’m doing fine.’ ”

In the call, Mr. Li did not specify why he was under investigation, referring only to “that case,” Ms. He said, adding that she took that to refer to claims that Mr. Li made, after arriving in India in October, that Chinese state security agents had coerced him into becoming an informant against fellow journalists and friends who worked for civic groups.

In October, Gui Minhai, a book publisher in Hong Kong who was born in China and holds Swedish citizenship, disappeared from his vacation home in the Thai coastal town of Pattaya. He was shown on Chinese television last month confessing to having violated his probation in a deadly road accident by leaving China in 2003.

In November, two Chinese dissidents in Thailand, Jiang Yefei and Dong Guanping, were sent back to China despite having been recognized as refugees by the United Nations refugee agency. The Chinese police later said that the men were suspected of crimes involving illegal border crossing.

Mr. Li had first gone to India, apparently hoping to obtain a visa to the United States, where he intended to apply for asylum. Failing that, he hoped to extend his stay in India. He succeeded at neither, and decided to go to Thailand. There, he hoped to receive official status as a refugee and qualify for settlement in another country, Ms. He said. To do that, he had to leave Thailand and re-enter with a new tourist visa.