The three are members of the Provisional Government of Vietnam, which Hanoi says is a terrorist group.
Xuan Loc Penitentiary has a reputation for mistreating and torturing inmates.
Trinh Ba Phuong invokes right to silence, refusing to cooperate with police.
During a virtual summit, members also agree to work together on post-COVID-19 pandemic economic recovery.
If convicted of murder, defendants could be given the death penalty.
Arrests come amid a broad crackdown six months before a key Communist Party gathering.
Nguyen Van Nghiem represented himself during his trial, refusing a lawyer.
Lawyers suspect police pressured two detained discussion page leaders into refusing legal counsel.
The intruders leave following heated arguments between the rival groups, with the state-affiliated branch backed by local police.
Huynh Anh Khoa and Nguyen Dang Thuong had managed a group with 46,000 followers which was shut down by authorities after their arrest.
Hai’s case has stirred public interest in one-party Vietnam, where the assembly typically rubber stamps ruling party decisions.
Le Huu Minh Tuan was arrested on June 12 and could face up to 20 years in prison.
The chief judge says Ho admitted guilt multiple times.
The move signals a tougher Chinese approach to enforcing its ban on fishing in areas it claims, and is the second such incident in just over two months.
Four others will be charged with obstructing officers in the performance of their duties during the deadly Jan. 9 clash that saw three police officers and a village elder killed.
Meanwhile, a Vietnamese coast guard vessel enters a disputed area in the Spratlys to monitor China's maritime militia.
NGOs in Cambodia and abroad call for release of remaining family member.
Chau Van Kham, an advocate for democracy in Vietnam, has not been seen or heard from by relatives of consular officials for almost four months.
Twelve countries, both dictatorships and democracies, had stifled debate in the name of fighting fake news.
Le Dinh Chuc, son of slain Dong Tam village elder Le Dinh Kinh, is recovering from injuries suffered in the Jan. 9 police assault, his lawyer says.