Prof Ajoy Roy yesterday expressed doubts over a video that depicts the Al-Qaeda in the Indian Subcontinent (AQIS) claiming responsibility for the murder of his son bloggerwriter Avi jit Roy.

"I do not know how much genuine the video is. Police were also not sure about its authenticity," he told The Daily Star over the phone, adding that the video might have been :irculated to mislead police vigilance.

The media yesterday reported the AQIS leader Asim LImar as saying that AQIS carried out the attacks on Avijit and "other blasphemers" in Bangladesh and Pakistan.

Prof Ajoy also said it does not matter who claimed responsibility. "Police's job is to find the attackers. Under whose umbrella the killers worked should come later," he said, adding that two to three persons were involved in the attack.

The Bangladesh-born US citizen was hacked to death an the Dhaka University campus on February 26 while returning from Amar Ekushey Granthamela-2015 with his wife Rafida Ahmed Banya, who was left badly injured.