Imelda Marcos' former secretary has been convicted of conspiring to sell a Monet painting that disappeared after Marcos' husband Ferdinand was ousted as Philippine president.
Vilma Bautista, 75, was found guilty by a New York court and is to be sentenced at a later date.
Bautista, who served as Marcos' New York-based secretary, sold the picture to a London gallery in 2010.
But the Philippine government says it owns the artwork.
Imelda Marcos accumulated a vast stock of valuable art and other luxury objects during her husband's 20-year corrupt dictatorship.
But much of it disappeared after the 1986 People Power revolution that saw him removed from power.
The Philippine government has sought to retrieve items that disappeared from government property, including from the Philippine Consulate townhouse in Manhattan, the District Attorney's office said in a statement.
"Bautista was found to be aware of and monitoring this campaign, even as she possessed some of the valuable works of art," it said.
Four paintings - including two Monets - acquired by the Marcos family had ended up in her possession.
Using false documents, she successfully sold Claude Monet's "Le Bassin aux Nymphease" to a London gallery for $32m (£20m).
"Bautista was found guilty of attempting to sell art she had possessed secretly for decades and knew to be stolen, and for selling a looted museum-quality painting for her personal enrichment," Manhattan District Attorney Cyrus Vance Jr said in the statement.
She was also convicted of document fraud and tax offences, and faces a lengthy prison sentence.