Eventually they, along with the rest of the world, learned that the Renoir had been stolen from the Baltimore Museum of Art in 1951.
Days before the Potomack auction, The Post found documents in the BMA's library showing that one of its biggest donors had lent the Renoir to the museum in the 1930s. That discovery led the BMA to find more internal records showing that its staff reported the Renoir's theft to Baltimore police in 1951.
According to the 1951 police report, between Nov. 16 and Nov. 17, "some one stole" the Renoir; there was no evidence of forced entry.
Potomack, which had told reporters and potential bidders that the Renoir could sell for as much as $100,000, canceled the auction and handed the painting over to the FBI.
In October, Quinn traveled to New Jersey for a business dinner and wound up talking with Robert Wittman, the retired founder and former senior investigator of the FBI's art crimes team.
He told Wittman about his employee's encounter with Fuqua. Wittman, who had been following the case of the "flea-market Renoir," was intrigued.
He passed along Quinn's contact information to the FBI case agent investigating the Renoir theft.
A few weeks later, the agent met with the Quinn's specialist.
"He wanted to know which date she came in," the specialist recalled. "And he was interested in the 'estate' aspect of her story."
The FBI declined to comment about its investigation.
Elizabeth Wainstein, the founder and president of the Potomack Company, said Fuqua has never strayed from her flea-market story since she called the auction house on July 17 to make her first appointment.
No one at Potomack pressed Fuqua on which flea market she visited, nor which vendor sold it to her. Wainstein said she and her staff were more concerned about whether the piece was real and whether it had been stolen.
That's why, she said, Potomack contacted Bernheim-Jeune, the Paris art gallery that keeps a compendium detailing the ownership histories of Renoir's works, and the London-based Art Loss Register, the world's largest private database of stolen and lost art. The Paris gallery confirmed that the painting was real, and the Art Loss Register reported that it was not on the register's list of stolen goods.
In an interview with The Post in early September, when she was still using the Renoir Girl pseudonym, Fuqua said that she'd called a New York auction house earlier but the firm didn't seem interested. She also mentioned that she'd visited another local auction house but declined to give any details.
"As soon as I walked in," she said, "there was some teenage girl who said it's probably not real."
Now, an Alexandria federal judge is set to decide who gets to keep the Renoir. It may come down to Fuqua or the Baltimore Museum of Art, which was lent the painting in 1937 by one of its largest donors, the late Saidie May.
In court papers, Fuqua argues that the government should recognize her as the painting's "innocent owner" as defined by federal law.
She claims she has only a layman's understanding of art and that she had no clue the painting she unwittingly bought was a real Renoir and subject to possible FBI forfeiture.
But Fuqua's mother, Marcia Fouquet, 84, ran an art studio for decades at her Fairfax home, where Fuqua also helped out for several years.
Her mother, who graduated from Goucher College in Baltimore with a fine arts degree in 1952 and earned a master's from the Maryland Institute College of Art in 1957, specialized in reproducing the works of famous painters, including Renoir.
Although the FBI is still investigating the case, the statute of limitations on the art theft has expired. But other related charges, such as possession and transportation of stolen property, could be filed, according to Robert Goldman, a former federal prosecutor who specialized in art theft.
Fuqua's attorney, T. Wayne Biggs, would not comment.
The Quinn's specialist still wonders about the unidentified man who came along with Fuqua. All she can recall was that the man was short. He looked middle-aged. He might have worn a ball cap.
The specialist does remember one thing: During his interview, the FBI agent seemed especially interested in the man as well.