I am new to this site but love it! Just back from a week touring mayan ruin sites in the Yucatan. Talk about Mystery! Anyway while there I read a fascinating thriller adventure novel "A Tourist in the Yucatan." It is fiction but the author the does a great job of wrapping the plot around the mystery of the ancient Maya. He includes the Bearded Man carving on the North Temple at Chichen Itza and even includes a viking conection! The book seemed well researched and I can vouch for the authors description of the Mayan sites as being spot on! here is the link to its amazon web page.
Edit; removed link