2 militant Islamist groups are behind the attacks, authorities say
                                
                                
                                    (Newser) -
                                    Since 2013 in Bangladesh, at least 39 activists, bloggers, foreigners, and religious minorities have been fatally struck down by  mysterious machete-wielding figures  on motorbikes. Now, authorities say they finally know who is behind the attacks, the  New York Times  reports. The chief of the police counterterrorism unit says that an...