People from all walks of life, including Roy's friends, relatives, well-wishers, teachers and students, gathered at the Dhaka University premises with flowers to pay their respect to the slain writer, who was on a visit to his native city in mid-February to attend a book fair.
Roy, known for his critique of religious extremism, was hacked to death in the university area by machete-wielding assailants, who attacked the Bangladeshi-origin writer as he was returning from the book fair with his wife on Thursday.
The coffin containing his remains was taken from the Dhaka Medical College and Hospital (DMCH) mortuary and placed on a platform erected at the university's premises.
After paying their tributes, Kabir, expressed indignation over the government's "failure to ensure the safety of the Bangladesh-born US-based bioengineer", reported bdnews24 for which Roy used to write columns regularly.
"Free thinking in Bangladesh is become a great danger, all the free thinkers are at great risk," writer-journalist Shahriar Kabir, a friend of Roy's father, said.
"We want to know why the government failed to ensure the safety of him, despite knowing that he had been facing threats from the Islamist radicals," he added.
The killing of the blogger -- said to be around 40 -- that apparently took place right in front of a police barricade put up to restrict vehicular movement on the adjacent road for the ongoing book fair sparked countrywide protests and international condemnation.
His wife and fellow blogger Rafida Ahmed Banna was seriously injured as she tried to defend him.
According to Roy's friends and family, Islamist radicals had been threatening him in recent weeks because he maintained a blog 'Mukto-mona' or 'Freemind' that highlighted humanist and rationalist ideas and condemned religious extremism.
No arrests have been made in the case so far.
People held a protest at the spot where he was killed and chanted slogans, demanding immediate arrest and speedy trial of the killers.
Roy's body was later handed over to Dhaka Medical College for medical research as per his wish.
This was the second such murder of a writer at the February Book Fair scene since the attack on famous Bangladeshi author and Dhaka University professor Humayun Azad who subsequently died of his wounds in Germany.
The militants later also killed another blogger Rajib Haidar in 2013.
The US has condemned Roy's murder in the "strongest terms", calling it "horrific in its brutality and cowardice".
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