By Brian Ellsworth MIAMI (Reuters) – The U.S. Coast Guard on Friday said it has returned 40 people to Cuba after intercepting two vessels near Florida while two people were being investigated for human smuggling. Increasing numbers of migrants are trying their luck at sea amid growing economic problems in Caribbean nations. The vessels were spotted near the Florida Keys on Sunday and on Tuesday. Two suspected smugglers were transferred to Homeland Security Investigations, a Coast Guard statement said. “People illegally entering the U.S. using smugglers put their lives in the hands of criminals…