By Abigail O’Leary The CEO of one of Nigeria ‘s largest banks was killed Friday along with his wife and son when a helicopter they were riding in crashed near Interstate 15 in Southern California’s Mojave Desert. Herbert Wigwe, chief executive of Access Bank, was among the six people on board when the aircraft went down shortly after 10 p.m. Bamofin Abimbola Ogunbanjo, former chair of NGX Group, the Nigerian stock exchange, was also killed. Their deaths were confirmed Saturday by Ngozi Okonjo-Iweala, a former Nigerian finance minister who is now the director-general of the World Trade Organiza…