GANZHOU, China >> The three Chinese investigators who went undercover at a factory that made Ivanka Trump shoes walked out of a Chinese police station Wednesday after a month behind bars, but face an uncertain future and threat of a trial.

Chinese authorities released the three on bail after allegedly breaking the law by using secret cameras and listening devices. It is extremely rare for individuals to be freed on bail if they had been criminally detained, a possible sign that they won’t be formally charged and put on trial.

Political dissidents and other activists who are released in China typically face restrictions on what they can do and say, including comments to the media.

“This is a way of keeping people under pressure, under police control, without subjected them to actual confinement,” said Jerome Cohen, a law professor at New York University and a Chinese human rights expert. “Whether they are prosecuted depends on how they behave.”

One of the activists, Hua Haifeng, was clearly relieved as he held his 3-year-old son outside the police station in Ganzhou, a city in southeastern Jiangxi province. But he was unwilling to talk much.

“I appreciate the media following my case the last month,” Hua told The Associated Press, “but I’m not ready to speak yet.”

Hua and his colleagues at the labor rights group China Labor Watch were preparing to publish a report alleging low pay, excessive overtime, crude verbal abuse and possible misuse of student labor at Huajian Group factories. The factories produced Ivanka Trump shoes, among other brands.

Huajian Group has denied allegations of excessive overtime and low wages. It says it stopped producing Ivanka Trump shoes months ago.

Hua and two other activists — Su Heng and Li Zhao — disappeared or were detained in late May. China Labor Watch said two were taken from a hotel room while the third was detained by customs officials in the southern city of Shenzhen while en route to Hong Kong.

NYU’s Cohen said he suspects the case wasn’t strong enough, and now may follow the pattern of the one against Ai Weiwei, the dissident artist who was released on bail in 2011 and never faced trial.

“I think this is face saving way to get rid of the case,” Cohen said. “Formally, the case will exist for another year, then it will be dropped unless these people misbehave.”

Li Qiang, founder of China Labor Watch, said the Huajian’s factory in Ganzhou was as among the worst he has seen in nearly two decades investigating labor abuses. His group says pay can be as low as a dollar an hour, in violation of China’s labor laws. According to China Labor Watch investigators, until recently, workers might get only two days off — or less — per month.

China Labor Watch said the company forced workers to sign fake pay stubs with inflated salary numbers and threatened to fire workers if they didn’t fill in questionnaires about working conditions with pre-approved answers.

Separately, the AP recently spoke to three workers at the Ganzhou factory — one current and two former employees — who confirmed some of what the labor group has reported.

The three worker told the AP that beatings were not unheard of, and that they had each witnessed a particularly gruesome scene one day: A worker with blood dripping his head after an angry manager had hit him with sharp end of a high-heeled shoe.

“There was a lot of blood. He went to the factory’s nurse station, passing by me,” said one of the former workers, who said he quit his job at the Huajian factory because of the long hours and low pay.

All three workers spoke to the AP on condition of anonymity, for fear of retribution or arrest.

The detention of the three activists prompted the U.S. State Department to call for their immediate release. At the time, Hua Chunying, spokeswoman for China’s Ministry of Foreign Affairs, said the men had been accused of using secret recording devices to disrupt normal commercial operations and would be dealt with under Chinese law.

“Other nations have no right to interfere in our judicial sovereignty and independence,” she said, adding, “the police found these people illegally possessed secret cameras, secret listening devices and other illegal monitoring devices.”

The White House directed any questions about the detainees on Wednesday to the State Department. Anna Richey-Allen, a State Department spokeswoman for East Asia and the Pacific, said: “We urge China to afford them the judicial and fair trial protections to which they are entitled.”

Ivanka Trump’s brand has declined to comment on the allegations or the detentions. Marc Fisher, which produces shoes for Ivanka Trump and other brands, has said it is looking into the allegations. Ivanka Trump’s lifestyle brand imports most of its merchandise from China, trade data show.

The detentions came as China has cracked down on perceived threats to the stability of its ruling Communist Party, particularly from sources with foreign ties such as China Labor Watch.

Faced with rising labor unrest and a slowing economy, Beijing has taken a stern approach to activism in southern China’s manufacturing belt and to human rights advocates generally, sparking a wave of reports about disappearances, public confessions, forced repatriation and torture in custody.

As he left the police station Wednesday, Hua was surrounded by family members. “I’m happy to be out,” he said. “I just want to spend some time with my family,”

Hua declined further comment but said he had not been mistreated.

AP reporters Gillian Wong in Beijing and Matthew Pennington in Washington contributed to this story.