kevin pimentel , 12 , shot his brother brady pimentel , 6 , dead on wednesday march 25 at their mobile home in hudson , florida .
he also wounded 16-year-old brother trevor pimentel in the leg before killing himself .
trevor attended the boys ' funeral in a wheelchair on wednesday .
kevin and trevor had been cooking about 6 pm but officials said they had not been arguing before the shootings .
their mother , helen campochiaro , 38 , was working one of her two jobs .
relatives say she was a single mom who kept a gun for protection and that the boys had been brought up with gun safety .
on a gofundme page set up one day before the shooting , campochiaro asked for help in raising a deposit for a new home .