Komrade was ultimately sent an additional $100,000, which was far short of expectations. The documents provided by the Ahsanis’ publicist show him growing more irritated and profane. His final words arrived on March 25: “Is time now for you feel some pain.”

Four days later, the police in Monaco came knocking.

Are “Le Figaro” and Komrade the same person, an extortionist masquerading as a whistle-blower, or perhaps a whistle-blower who dabbles in extortion? Lawyers for the Ahsanis think the answer is “yes,” and they have tried to turn the extortion plot into a media ethics matter, suggesting that The Age was relying on information used to commit blackmail.

Editors at The Age, which is owned by Fairfax Media, counter that the Ahsanis never mentioned blackmail when contacted with prepublication questions. They add that “Le Figaro” did not ask for money, nor did anyone else reached by reporters after they started digging into the story. These additional sources include former employees of Unaoil, according to Mr. McKenzie.

“We have no evidence that our sources were involved in extortion attempts, and any alleged extortion bid has nothing to do with Fairfax Media,” Alex Lavelle, editor of The Age, said in an email. “We maintain our stories on Unaoil are true, in the public interest and unimpeachable.”

For the Serious Fraud Office, the stakes in the Unaoil case are high. It has struggled for respect in the realm of corporate prosecutions and has badly lagged behind the Department of Justice in foreign corruption actions. A spokesman for the office noted an in email that the Bribery Act, the country’s answer to the Foreign Corrupt Practices Act, didn’t go into effect until 2011.

“We have secured successful outcomes in all foreign bribery cases brought under the law,” said the spokesman, Adam Lilley.

For the Ahsanis, the stakes are far higher. Monaco is a signatory to the European Convention on Extradition, which means the family is shadowed by the possibility that the local police may one day return, and this time hand the Ahsanis over to the British authorities, who could seek prison sentences.