Bangladeshi police are continuing to investigate Friday's deadly attack on a Dhaka cafe, amid shock at the elite background of most of the suspects.

Twenty hostages, two policemen and six suspects were killed in the raid. One suspect was arrested.

So what motivated these attackers to carry out such a brutal crime? Sanjoy Majumder has been trying to find out.

Video produced by Pratiksha Ghildial, shot and edited by Sanjay Ganguly.