Tamerlan Tsarnaev

James Blitz

Images of two suspects at an FBI press conference on April 18  (Darren McCollester/Getty)

Images of the two suspects at an FBI press conference on April 18 (Darren McCollester/Getty)

Two brothers, Dzhokhar and Tamerlan Tsarnaev, are suspected by US law enforcement officials of carrying out the bombing of the Boston marathon on Monday. The elder brother Tamerlan died in the course of an early morning car chase. The younger is now the subject of a manhunt. If we assume that these two men were indeed the perpetrators of the killings, establishing the motive for the attacks will soon become the biggest challenge for the US authorities.

Over the next few hours and days the US police and security services will be searching properties and buildings associated with the two men, analysing the content of computers and laptops, interviewing family and friends – all in order to build up a picture of why the two brothers acted as they did. Only then will the US government be able to work out the security and policy implications of the horrific events Boston has seen this week.

As of now, no form conclusion can be drawn. What can be said is that the two brothers will have had one of three possible motives. Read more