An abstract painting by Mexican artist Rufino Tamayo, found lying in trash on the street on Manhattan's Upper West Side, could be worth up to $1 million.

The passer-by, who had no idea of what she was looking at, picked up the painting and brought it home because "it had a strange power."

It turned out that the 1970 painting, "Tres Personajes" (Three People), had been stolen more than 20 years ago and was the subject of an FBI investigation. It's now back in the hands of the rightful owners, who have decided to sell it at auction.

The auction house says it could bring up to $1 million when it is sold next month.

Sotheby's expert August Uribe had featured it on PBS's "Antiques Roadshow FYI" in 2005 as a missing masterpiece after it was stolen.

"I know nothing of modern art but it didn't seem right for any piece of art to be discarded like that," Elizabeth Gibson, who found the brightly colored work while on her morning walk four years ago, told Sotheby's.

She said she learned of the work's worth after doing some Internet research, which eventually led her to the Antiques Roadshow Web site.

Sotheby's says "Tres Personajes" is an important work that represents the artist's mature period. It will be sold at its Latin American Art auction on Nov. 20.

The original owners, an anonymous Houston couple, purchased the painting in 1977 at Sotheby's. It was stolen in 1987, and the couple reported the theft to Houston and federal authorities. The work also was posted on the databases of the International Foundation for Art Research and the Art Loss Register. But no credible leads had turned up.

A Tamayo retrospective starts Friday at the Museo Tamayo Arte Contemporaneo in Mexico City.

Tamayo died in 1991.