The main suspect in last week's killing of U.S. blogger Avijit Roy in Dhaka, Bangladesh, was arrested Monday by the country's anti-terrorism forces, reports said, citing authorities. The atheist blogger was hacked to death on Thursday by suspected Islamists, igniting religious tensions in the country.

Forces from the Rapid Action Battalion (RAB) arrested Farabi Shafiur Rahman at a bus stop in Dhaka, Reuters reported. Rahman was previously jailed for his suspected involvement in another blogger’s death, but was later released on bail. Roy, an engineer by profession and a U.S. citizen, was hacked to death by assailants wielding machetes near Dhaka University. Roy's wife, Rafida Ahmed, who was seriously injured in Thursday's attack, is still in the hospital.

An RAB spokesman said Rahman had confessed to making threatening remarks against Roy. Rahman allegedly posted, “It’s a holy duty of Bengali Muslims to kill Avijit,” on Facebook last year, police said, according to reports.

Dhaka Metropolitan Police Commissioner Asaduzzaman Mia told, a local news website, that Roy's killers could be traced back to Dhaka University. “Those who had come to kill [Roy] with machetes were not outsiders. They were university-centric,” Mia said.

Ajay Roy, Avijit’s father, filed a case with local police on Friday. He did not name suspects, but alleged that the Jamaat-e-Islami political party was involved. Meanwhile, an Islamist group named “Ansar Bangla 7” reportedly claimed the killing as an achievement on Twitter, describing it as punishment for Roy’s “crime against Islam.”

The government of Prime Minister Sheikh Hasina, which had previously vowed to maintain democratic secularism, has been criticized for its perceived capitulation to hardline Islam, after four bloggers were arrested in 2013 for “hurting the religious feelings of people,” The Committee to Protect Journalists reported. Other bloggers were also reportedly interviewed by detectives and had their online posts deleted.

Roy ran a blog called Mukto-Mona (“Free-Mind”), for which he and his wife reportedly received death threats for writing against religious communalism and exploitation. In an article to be published posthumously in The Free Inquiry, a magazine, he criticized the “virus of faith” for warping behavior toward violence.

“The phrase “religion of peace” gives me a belly laugh nowadays, and the association of Islam’s followers with terrorism never surprises me,” he wrote.