sentences:  The looters dug large trenches cutting through the most important temples; at the height of the looting in the late 1970s as many as 80 workers were employed, funded by a wealthy private collector.Archaeologist Ian Graham travelled to Río Azul in 1981 to follow up rumours of the looting and document the damage; as a result of his survey the Guatemalan government stationed custodians at the site.Richard Adams started formal investigations of Río Azul in 1983, beginning the five-year Río Azul Project, which finished in 1987.