Students Against Discrimination staged nationwide rallies last month that ended in a police crackdown and the deaths of at least 206 people, according to an AFP count of police and hospital data.
The group's leadership were among thousands picked up in the police dragnet that followed some of the worst unrest of Prime Minister Sheikh Hasina's 15-year tenure.
«All six quota movement coordinators have been returned to their families this afternoon,» deputy commissioner Junaed Alam Sarkar said.
Principal leader Nahid Islam and two others had been forcibly discharged from a hospital in the capital Dhaka last Friday by plainclothes detectives and taken to an unknown location.
His father Badrul Islam confirmed to AFP that Nahid had returned home early Thursday afternoon but did not give any more details.
Three others were detained in the following days with the government saying at the time they had been held for their own safety.
Justice minister Anisul Huq told AFP on Thursday that all six had volunteered to be in police custody.
«They came willingly. They said they wanted to go. They are allowed to return to their parents,» he added.
Hasina's government restored order after deploying troops, imposing a curfew and shutting down the mobile internet network across the country of 170 million for 11 days.
More than 10,000 people were arrested in the wake of the unrest, according to local media.
— 'Arbitrary and unlawful' -
Small and scattered protests resumed in cities around Bangladesh this week after other