- Police say the suspect posted photos of the crime scene
- He also threatened Roy in social media posts, his family said
The person, Farabi Shafiur Rahman, had called for Avijit Roy's death in numerous Facebook posts, according to Roy's parents.
And within minutes after the Thursday attack, Rahman posted photos of the crime scene, said Col. Ziaul Ahsan of Bangladesh's elite anti-crime unit, the Rapid Action Battalion.
In a Facebook comment last year, Rahman allegedly wrote, "Avijit Roy lives in America. So it's not possible to kill him now. But when he returns home, he will be killed then."
In an earlier post, the same person wrote, "It's a Bengali Muslims holy duty to kill Avijit."
Extremists resented Roy for openly and regularly criticizing religion in his blog
. They threatened to kill him if he came home from the United States to visit.
As usual, Roy defied the threats and departed his home in suburban Atlanta for Dhaka, where he appeared at a speaking engagement about his latest books -- one of them titled "The Virus of Faith." He has written seven books in all.
Roy was killed Thursday as he walked back from a book fair with his wife. Assailants plunged machetes and knives into Roy and his wife, killing him and leaving her bloodied and missing a finger.
Witnesses said no one came to the couple's aid as they were hacked down.
Rahman, the man in custody, also allegedly posted threats against the owner of the online bookstore, Rokomari.com, forcing it to stop selling Roy's books.
And last year, he was detained -- then released -- for comments he allegedly made in support of the death of another blogger, Ahmed Rajib Haider
Like Roy, Haider too was hacked to death. He too had written critically about religion on his blog.