The painting "Tres Personajes" by Rufino Tamayo was discovered in 2003 by Elizabeth Gibson, who spotted it on her morning walk on Manhattan's Upper West Side. She said she took it home because "even though I didn't understand it, I knew it had power."
The brightly colored abstract work was purchased for $1,049,000 by an unidentified private American collector bidding by phone at Sotheby's Latin American Art sale Tuesday night.
Gibson spent four years trying to find out about the painting, finally discovering on the "Antiques Roadshow" Web site that it had been featured on the popular PBS program and described as a missing masterpiece stolen in 1989.
Gibson has received a $15,000 reward for turning in "Tres Personajes" and also will get a percentage of the sale price.
Painted in 1970, "Tres Personajes" was purchased by a Houston collector for $55,000 as a gift for his wife at a Sotheby's auction in 1977. Ten years later, as the couple was moving to a new home, it was stolen from storage.
The husband has since died, and the widow, who wished to remain anonymous, decided to sell it.
Tamayo was born in 1899 and died in 1991. His early work has similarities to that of famed 20th century muralist Diego Rivera. His later work features the vivid colors and expressions of his native state of Oaxaca.