But with at least five Marias living in the building, the mystery persists.
Reporters and cameramen descended on Republica de la India street after a South Carolina newspaper found the address in the couple's steamy e-mails. But the paper, called The State, did not publish her last name, leaving the rest of the pack scrambling for clues and complaining about their stakeout duty on one of the coldest days of the Argentine winter.
Is it Maria the soy and fruit exporter or Maria the former television journalist? Maria the architect or Maria the artist? Or maybe the Maria who poses next to an Argentine flag on her Facebook page?
Hopes briefly rise as one woman walks out saying "Yes, I'm Maria!"
"But I'm not the one you're looking for!" she quickly adds, giggling her way down the sidewalk.
The building's doormen tantalize reporters with vague statements, giving nothing away. Luxury cars with tinted windows enter and leave the garage. Cameras record everyone coming and going, in the hope of snaring the image U.S. media are desperate to obtain — the first pictures of the woman who may have helped ruin the governor's political career.
Even the shop girl in a designer boutique on the ground floor pushes the door shut in a reporter's face, saying "No, No, No" when asked if Maria is a client.
An Argentine Web site shows footage of a freelance television journalist in New York it says is her. A gossip column reports a nearby bar owner's claim that the amorous couple shared wine-filled evenings there last week. But the journalist is a brunette, and the bar owner describes a green-eyed blonde.
And the bartender on duty Thursday says Maria has not been with the governor recently.
Finally, another doorman comes on duty — Everard Alvarez — who denies that the woman on Facebook has anything to do with this tale.
Alvarez then confirms that the Maria named in Argentina's leading newspapers lives in the building — but he won't say whether the governor visited her during his trip to Argentina last week.
"It's a very large building, many people come and go all the time," he says.
Asked about her appearance, he says: "I look at my wife, I don't look at other women." The governor's Maria, he adds, is "a very elegant woman, very well-mannered, has a routine that includes jogging frequently."