Detectives picked up coordinator of Khulna Sramik, Krishak, Chhatra-Janata Oikya Parishad Ruhul Amin and its organizer Niaz Murshed from their residence on Friday night and later freed Niaz at 12:30 am.

Niaz Murshed told reporters that a team of DB police and KMP picked them up from their rented house and took to them DB office.

Deputy Commissioner of Khulna DB police BM Nururzzamn said a DB inspector filed a case against Ruhul Amin under the Digital Security Act(DSA) for various reasons including destabilizing the state.

Also read: Writer Mushtaq, arrested under DSA, dies in custody

He will be produced before a court with a remand prayer, he said .

Meanwhile, leaders and activists of Sramik, Krishak, Chhatra-Janata Oikya Parishad brought out a protest procession in the city protesting Ruhul Amin’s arrest.

Mushtaq reportedly suffered a heart attack inside his cell at Kashimpur prison on Thursday evening.

Also read: Panel to probe custodial death of writer Mushtaq

"He was rushed to Shaheed Tajuddin Medical College Hospital where he was declared brought dead," Senior Jail Superintendent Md Gias Uddin said.

An unnatural death case has been filed with the Gazipur Metropolitan Police's Sadar Police Station in connection with Mushtaq's custodial death.

The 53-year-old writer, who published the book "Kumir Chaasher Diary" under the pen name Michael Kumir Thakur, was picked up by Rapid Action Battalion (RAB) personnel from his Lalmatia home on May 2, allegedly for posts over the handling of the Covid-19 pandemic.

Also read: Writer Mushtaq's death in custody triggers protests

On August 20, he was shifted to Kashimpur prison, Gias Uddin said.

Calls for Mushtaq's release were widespread and sustained throughout his time in prison. Soon after his arrest, more than 300 dignitaries in Bangladesh issued a joint statement demanding his release, including cartoonist Ahmed Kishore.

However, his bail applications were turned down on at least on four occasions.

Also read: Mushtaq’s death: Protests rage in Dhaka for 2nd day

Left-leaning student bodies, including Bangladesh Chhatra Front, Chhatra Federation and Bangladesh Students Rights Protection Council, on Saturday staged demonstrations on the Dhaka University campus for the 2nd consecutive day protesting the death of writer Mushtaq Ahmed under police custody.