Police authorities on Thursday launched an investigation into the murder of a prominent Rohingya rights activist at a refugee camp in south-eastern Bangladesh.

“We have beefed up security in and around the camps, and began an investigation into the killing,’’ officer Shakil Ahmed told dpa by phone.

The investigators, however, could not yet discern the motive behind the murder of Mohib Ullah, 50, the head of Arakan Rohingya Society for Peace and Human Rights (ARSPH), he said.

Ullah, a schoolteacher turned rights activist, was gunned down late on Wednesday by unidentified assailants inside the refugee camp in the district of Cox’s Bazar.

Cox’s Bazar is home to hundreds of thousands of Rohingya Muslims who fled persecution in neighboring Buddhist-majority Myanmar.

Ahmed said additional armed police officers were deployed to enhance surveillance in the camps.

Television footage shows makeshift checkpoints were set up at the entry points of most of the 34 refugee camps, most shops are shut, according to the footage.

The victim’s younger brother, Habib Ullah, blamed the Arakan Rohingya Solidarity Army (ARSA), an armed insurgent Rohingya group, for his brother’s killing.

He told broadcaster Channel24 that he was with his brother when the assailants fired guns on Mohib Ullah.

He also claimed that he recognized some of the attackers, who belong to the ARSA, a group blamed for carrying out the attack on security checkpoints in northern Rakhine state.

The attack reportedly prompted the Myanmar military to launch a crackdown against the Rohingya in August 2017.

Nearly 750,000 Rohingya Muslims fled the crackdown and crossed into Bangladesh, which now hosts more than one million Rohingya.

Ullah, who was also among them, mobilized the refugees in Bangladeshi camps under the banner of ARSPH, having more than 300 activists working for the Rohingya rights.

The organization played a role in plans to repatriate Rohingya Muslims to Myanmar, according to a government report.

Ullah is one of a group of victims of religious persecution from around the world that met former U.S. president, Donald Trump at the White House in 2019 when he asked the U.S to help his beleaguered people.

The European Union Delegation to Bangladesh, in a tweet, had sent its condolences regarding the death and urged the Bangladeshi authorities to bring the attackers to justice.

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Bangladeshi rights activist Nur Khan said some insurgent groups that oppose a peaceful solution to the Rohingya crisis might be behind the murder of Ullah, who always looked for non-violent ways to end the problem.

“It is a signal that the extremists were trying to take control over the refugees in Bangladesh,” Nur said, adding that he fears that the murder would further delay the stalled process of Rohingya repatriation to Myanmar.