Shared para­noid dis­order might also explain why the two brothers did not ini­tially plan for a quick get­away after the bombing. “They might have fan­ta­sized that God would take care of them,” Bursz­tajn said, and enable them to escape being iden­ti­fied as the bombers. Or they might simply have been care­less in their planning.

The psy­chi­atric con­di­tion, how­ever, is uncommon, and a far more plau­sible sce­nario is that the brothers were embold­ened by each other.

They may believe that murder is wrong, but their sense of alle­giance and loy­alty to each other or the group may super­sede that sense of right and wrong,” said James Alan Fox, a crim­i­nology pro­fessor at North­eastern University.

Awful crimes may be com­mitted just for the sake of a per­verted kind of bonding,” Fox said. Crim­i­nals often com­part­men­talize, dividing the world into those they care about and everyone else.

And just as some men who commit group rape would never rape someone on their own, some people only kill in pairs. One brother may have been looking for his younger brother’s admi­ra­tion, while the other was looking for his older brother’s approval.

I think they brought out the worst in each other,” Fox said. “I’m not sure either would have com­mitted murder on his own.”

Read the article at The Boston Globe →