She and other family members say repeated appeals for medical parole have gone unanswered.
She says Hung has been hospitalized and medicated against his will.
The April 2016 spill of toxic waste from a steel plant polluted the coastline of four Vietnamese provinces, leaving thousands out of work.
Nguyen, detained since July 2018, has not been given access to a lawyer or his family.
The search warrant, issued in January, is now almost five months old, pointing to an unusual delay in gathering evidence in the case.
Ha Van Thanh has been on the run for more than a year after Vietnamese police began rounding up Formosa Company protesters.
Nguyen Ngoc Anh found guilty of spreading information to “combat the state.”
Minister hints at a return to forced rehab centers during a National Assembly hearing.
US delegates to an annual human rights dialogue with Vietnam point to a rising number of prosecutions over the last two years.
Meanwhile, Vietnamese police arrest a Catholic schoolteacher on unknown charges, taking him into custody while he was eating breakfast with his son.
The rights group calls for his immediate and unconditional release, calling him a prisoner of conscience who should never have been arrested.
Hoa, who had blogged and produced videos for RFA, was beaten and choked by prison guards and placed in solitary confinement earlier in May.
While rallying against polluting companies and SEZ plans, protesters nabbed on charges of disrupting public order and destruction of state property.
The public is wary that Hanoi will bend to Beijing’s influence if it accepts too many loans.
Police keep them under watch, barricade them in their homes, in the run-up to an annual human rights dialogue, sources say.
Former prisoners and other activists are meanwhile blocked from meeting with members of a US human rights delegation.
Democracy advocate Le Anh Hung is sent back for continued observation for what authorities call his 'delusions.'
Human rights groups express concern for the safety of three anti-monarchy activists.
Huynh Duc Thanh Binh, taken into custody along with US citizen Michael Nguyen, has been charged with working to subvert state authority.
Nguyen Huu Vinh, better known as Anh Ba Sam, had been sentenced for 'abusing democratice freedoms' by posting articles criticizing the government.
Activist Bach Hong Quyen, safe in Canada, describes how he escaped being spirited back to Vietnam during a precarious stay in Thailand.
Bach Hong Quyen had feared being sent back to Vietnam after helping a dissident blogger later abducted by Vietnamese police.
Meanwhile, Myanmar and China should remain on the State Department's blacklist, the group says.
Jakarta summons Hanoi emissary following weekend confrontation at sea.
Le Anh Hung, a member of the Brotherhood for Democracy, had been put under observation for 'delusions,' his lawyer says.
Hanoi prison officer says authorities are under official order to deny Truong Duy Nhat access to supplies, but decline to show paperwork.
Legal expert and entrepreneur Nguyen Bac Truyen is serving 11 years in jail.
But leaked documents show the tribunal awarded Trinh Vinh Binh nearly U.S. $40 million in damages.
In Loc Hung schools, students are forced to learn that demolishing their homes was necessary.
Former prosecutor’s attack sparks public outcry after video goes viral.