he is running a 50-mile ultramarathon to try to save a boy. >>> the anatomy of violence. how does an innocent child grow up to be an accused boston bomber or any criminal for that matter? what is happening in their brains? scientists today say biology plays a bigger role than we once thought. >> in the wake of tragedy come the inevitable question. what makes a killer. is there a switch that turns on a rampage? and why. why would someone do this? >> you can just say the person's evil. i think that's 13th century thinking. i think we moved beyond that. >> he's a criminologist and also the author of a new book "ana "anatomy of violence." he says there are biological explanations for violence. he is convinced that brain dysfunction may, in part, explain the terror unleashed in boston. >> completely normal people who decided one day, you know what, we want to create mayhem. i don't think so. i think it's more complicated than that. >> you know, when you see all the tragedies that have happened recently with tsarnaev or adam lanza. from your background and your experience, what

he is running a 50-mile ultramarathon to try to save a boy. >>> the anatomy of violence. child grow up to be an accused boston bomber or any criminal for

. >>> a group of ultramarathoners have a plan to help victims of the boston marathon bombings. the men ran double and triple marathons to raise money for the 8-year-old boy who died in the bombing as well as another man who lost both his legs. now the plan is to run the money to those families. that's a distance of 450 miles. >> 90% is mental, the other 10% is mental. so part of it is in your mind. the other 10%, you've got to be out of your mind. >> the men are doing this as a relay splitting the distance in 26-mile increments. they say by the time they reached boston, they will have each done between 10 and 12 marathons. expect the entire journey to take them just five days. the strength. >> wow, unbelievable. >> isn't that amazing? >> hopefully they will fly their way home. >> i hope so. >> check the forecast with meteorologist christina loren. good day for a run but not that long. >> yeah, not that long. we have major changes headed our way. if you wanted to go for a quick run today, you'll get the best of the best, as the warm-up really kicks in. getting into the end of th

he ran a 50-mile ultramarathon last saturday to raise awareness and funding for urgent research. >> well-done! >> as you see right there johnny made it. and he told me, you know, when you set your sights on a cause like this, there's no backing out. it's just too important. i can tell you firsthand running with a real sense of mission it can be very fulfilling. so here's an idea for you today, find something you love to do and do it for a cause. there are crowd-funding websites like crowdrise, gofundme. johnny did it for jonah. who will you help to chase life? that's going to do it for us today. when you get a minute, check out this, the featured fit nation of the cnn ipad app. right now keep it here for a check of your top stories. >>> from cnn world headquarters in atlanta, this is "cnn sunday morning." >> do you worry now that people will always suspect that you actually did have a role? >> speaking out for the very first time in a cnn world exclusive, pedro and onil castro, brothers of the accused rapist and kidnapper ariel castro sit down with martin savidge, what they say about their br

a group of ultramarathoners in washington, d.c. have a bold plan to help victims of the boston marathon bombings. the men ran double and triple marathons to raise money for the families of martin richard, the 8-year-old boy who died in the bombing, as well as another man who lost both his legs. now, the plan is to run the money to those families and that's a distance of 450 miles. >>> 90% is mental. the other 10% is mental. so part of it is in your mind. the other 10% is, you have to be out of your mind. >> the men are doing this as a relay splitting the distance into 26-mile increments. by the time they reach boston, they will have each done between 10-12 marathons. they expect the entire journey to take them five days. >> and how many pairs of shoes? >> and how many massages there after? >> hopefully, they will fly home. they deserve it. we want to check the forecast with meteorologist, christina loren. you said it was breezy. >>> it is a tad breezy out there. good morning to you, laura and marla. good morning to you at home. tak