“It was not a heavy kick,” Mr. Hua said. “I think he just wanted to warn me and didn’t want me to call for meeting the police.”

During the weeks that followed, Mr. Hua said, he was interrogated about 16 times, each time for periods between 30 minutes and three hours. He was not allowed access to a lawyer for the first week of his detention.

A State Department spokeswoman urged China on June 5, a week after the activists had been detained, to release the men and grant them legal protections and a fair trial. China rejected that request as an interference in its internal affairs, but soon allowed Mr. Hua access to a lawyer for the first time. China Labor Watch says the defendants have had very limited access to lawyers, and that the authorities have pressured the lawyers not to speak about the case.

The State Department spokeswoman, Alicia Edwards, also said that American companies benefited when undercover labor investigators could help make sure that Chinese manufacturers were respecting labor laws.

Ms. Trump has stayed silent about the case since the original detentions, while her company has repeatedly declined to comment and did so again Monday.

Local officials in Ganzhou released all three on bail from the detention facility on June 28, pending a trial, but have not yet indicted the men on specific charges or set a trial date. The Chinese authorities have repeatedly declined to comment on the case and had no comment Monday night. Chinese censors have deleted coverage of the case in mainland Chinese online media.

Mr. Hua said that he had decided during his four-week detention that he would speak to the news media after his release because he thought the public had a right to know about what he described as excessive work hours and other unfair or illegal labor practices at Huajian.