Leonard Glenn Francis, a wealthy Malaysian contractor at the heart of one of the United States Navy’s largest bribery scandals in decades, seemed to have stepped right off the set of “Casablanca.”

At 6 feet 3 inches and 350 pounds, Mr. Francis hosted dinners at luxury hotels in Malaysia, Singapore and Hong Kong for senior officers who knew him as Fat Leonard, dispensing boxes of Cuban cigars and dropping the names of admirals he knew, senior Navy officers said.

But as his reputation for lavish parties spread, so too did warnings about his business practices, according to Navy officials and court documents. Emails obtained by criminal investigators show that from 2009 to early 2011, several ship crews and contracting officials filed complaints about his “gold-plated” fees for fuel, port security and other services. In 2010, the Naval Criminal Investigative Service opened investigations into questionable charges in Thailand and Japan by his company, documents show.

Despite those red flags, in June 2011, the Navy awarded Mr. Francis $200 million in contracts, giving him control over providing supplies and dockside services for its fleet across the Pacific.