French judges have ended their investigation into the substantial assets of Gabon's late president Omar Bongo and his family, none of whom have been charged, sources close to the case said Wednesday. French prosecutors have been investigating since 2010 whether the fortunes amassed in France by the ruling elites of three oil-rich African countries - Congo Brazzaville, Equatorial Guinea and Gabon - were built up with money siphoned from public coffers.