Isabella Stewart Gardner Art Heist- who did it?

On March 18th, 1990 one of the largest art thefts in history took place in Boston. 13 priceless artworks were taken. Despite decades of investigations, these pieces remain missing. Who did it and why?Jerry and Rita Alter were a retired New York city couple was believed to have been involved in several art thefts, including the theft of Woman-Ochre by Willem de Kooning from the University of Arizona Museum of Art. after the stolen painting was found in their New Mexico home. The FBI has confirmed that two other paintings stolen from the Harwood Museum of Art in Taos, New Mexico, were also in the Alters' possession. Did they do it? Are they linked to any other crimes?Sources: https://www.gardnermuseum.org/organization/theftThe Theft | Isabella Stewart Gardner MuseumIsabella Stewart Gardner theft at fbi.gov“This is a Robbery: the World’s Biggest Art Heist” on Neflixhttps://www.bpl.org/blogs/post/bostons-greatest-unsolved-mystery-the-gardner-museum-art-heist/“The Thief Collector” documentary“The Gardner Heist” by Ulrich Boserhttps://www.bostonglobe.com/metro/Gardner-Museum-art-heist/wikipedia