Izyiah Plummer, 19, of Atlantic City stopped working at Caesars on July 9, the Press of Atlantic City reported. Twelve days later, the casino was robbed of more than $180,000 by two men who brandished guns.
Plummer and Dwayne Morgan, 20, of Pleasantville were arrested last week. Aaron Evans, 23, also of Pleasantville, joined them in jail the next day.
Monique Kelly, 19, of Pleasantville, and Lance Rogers, 20, of Atlantic City have also been charged.
Morgan worked as a convention service attendant at the Tropicana and Kelly worked at Harrah's.
Prosecutors said Wednesday the investigation remained open and more arrests are possible.