Shenzhen police say they have completed their investigation into 12 young Hong Kong people arrested for allegedly entering mainland waters illegally, and the case has been passed to prosecutors.
In a notice published on Friday, the Yantian Detention Centre said the Hongkongers have now been "handed over" to Yantian district prosecutors "in accordance with the law".
The group were captured by the Guangdong coast guard on August 23 as they travelled on a speedboat. They were reportedly trying to make their way to Taiwan.
Eleven of them had been facing prosecution in connection with anti-government protests, while one had been arrested, but not charged, under the national security law.
While 10 members of the group are now accused of entering the mainland's jurisdiction illegally, two face a more serious charge of organising the illegal crossing, prosecutors said earlier.
Beatrice Li, sister of Andy Li, one of the detained, told the Reuters news agency on Friday: "It is not a fair legal process that they are undergoing."
The father of detainee Cheng Tsz-ho said: "The faster the trial, the faster we can know how long they will be detained ... I hope we can ... have a fair and just judicial trial.”
Mainland lawyers told RTHK that it could be between one and six months before the case reaches court.
Despite numerous attempts, relatives of the detainees have not managed to secure any visits with them, and lawyers appointed by the families have been refused access to those held.
Last week, relatives of some of the 12 received letters from the detainees, hailing the conditions in the detention centre as well as their treatment by the authorities.
But a concern group linked to the families said the handwritten letters all had similar content as well as "suspicious wording", including phrases not usually used by Hongkongers and simplified Chinese characters.