i still wonder why they did it. conspiracy theories anyone?

before their identities were revealed, i sort of thought they could be those people who didn't want stricter gun control laws trying to prove you don't need a gun to wreak havoc.

when information about the younger kid started coming out, i thought that they may be some sort of manchurian candidates or sleeper agents by some evil organization

or it could just be the elder brother bullying the younger one into coming with him to the marathon to do the deed together.

got this pic from another forum where the suspect and the bag was seen with the little boy who died nearby