People gather on the spot where Bangladeshi blogger Avijit Roy was killed in  Dhaka, Bangladesh,  on Thursday evening. Roy, a prominent Bangladeshi-US blogger, was attacked with his wife by machete-wielding assailants while walking in the streets. Photograph: Abir Abdullah/EPA

A prominent Bangladeshi-American blogger known for speaking out against religious extremism has been hacked to death as he walked through Bangladesh’s(...)