As he does every year on the anniversary of his mother’s killing, Steve Johnston finds himself reliving each detail of that day.June 17 marked 40 years, but it sadly has remained fresh in Johnston’s mind for a reason beyond his personal loss.His mother was taken by a mass shooting in Rhode Island at a time such crimes were an aberration.But now each one, from Columbine to Parkland to the Annapolis newspaper attack, brings him flashbacks.