Ever heard of Philip Schneider? (b.1947 d.1996). He worked as a Geologist and Structural Engineer for the US Government and claimed he was involved in building deep underground military bases around the US. He went public and told of his experiences about government cover-ups, black budgets and UFOs. He is quoted as saying:

“The alien agenda is the complete take over of this planet, the killing off of five sixths, to seven eighths of the worlds population by the year 2029. The US military have known about this for forty five years, they’ve told no one.”

He said this in 1995, less than a year later he was found murdered.

You can see him making this claim here: