As the story goes, Saturno was resting (mostly from the heat) near the site about a year ago, and took shelter in a looters tunnel that had been dug into the structure. He happened to look up and noticed this mural, which is about 18 sq. meters, and then "just started laughing".
He rushed back to the States, got some funds, and started paying to keep looters away from the site, while he put together an emergency excavation expedition (with the help of National Geographic).
While Mayan culture produced their finest and most well-known works during the period 250-950 AD, this painting has been dated to 100 AD, and will provide important new information into the "Preclassic period of the Maya", about which less is understood.
The site, long ago raided by looters for artifacts that could be carried away, is called "San Bartolo", and lies in a sector of Guatamala where Mayans are believed to have lived from about 2000 bc, until 250 AD. It will continue to be excavated for more insight into the early days of the Mayan empire.
The Washington Post also has an
article on this interesting find.