DARTMOUTH, Mass. - Working out at the gym at their sleepy New England college, two students chatted about how "crazy" it was that bombs exploded at the Boston Marathon. Three days later, one of them was named a prime suspect.Returning to campus on Sunday after being evacuated on Friday during a massive manhunt for the bombers, students at the University of Massachusetts-Dartmouth swapped recollections of seeing Dzhokhar Tsarnaev, 19, back in the dorm, at class and in the gym in the aftermath of the bombings.Tsarnaev was working out in the gym from 8 to 10 p.m. on Tuesday, listening to music on his iPod, when he struck up a conversation with fellow sophomore Zach Bettencourt."It's crazy this is happening now," Bettencourt recalled Tsarnaev telling him when the bombings came up. "This (these bombings) is so easy to do. These tragedies happen all the time in Afghanistan and Iraq."