Swindles in which someone overseas seeks access to a person’s bank account are so well known that most potential victims can spot them in seconds. But one man found success by tweaking the formula, prosecutors say: Rather than trying to dupe an account holder into giving up information, he duped the bank. And instead of swindling a person, he tried to rob a country — of $27 million. To carry out the elaborate scheme, prosecutors in New York said on Friday, the man, identified as Paul Gabriel Amos, 37, a Nigerian citizen who lived in Singapore, worked with others to...