heist occurred march 1 in wilson county , north carolina .
armored truck traveling from miami to boston was robbed by three men .
275 pounds of gold worth nearly $ 5 million stolen .
a 26-pound gold bar worth $ 500,000 now recovered in south florida .
police previously suspected it was an inside job .
the guards had pulled over because one felt sick .
goods transported with company , transvalue , insured up to $ 100 million .