Exxon executives were warned of possible catastrophe from greenhouse effect, then led efforts to block solutions

Exxon's Own Research Confirmed Fossil Fuels' Role in Global Warming Decades Ago. Source: Inside Climate News (link here)

I do not know how much truth, and how much spin or fabrication, is in this story. But if it pans out even in a tenth part then these people have attempted to kill millions - for profit.

From the original article:
At a meeting in Exxon Corporation's headquarters, a senior company scientist named James F. Black addressed an audience of powerful oilmen. Speaking without a text as he flipped through detailed slides, Black delivered a sobering message: carbon dioxide from the world's use of fossil fuels would warm the planet and could eventually endanger humanity.
"In the first place, there is general scientific agreement that the most likely manner in which mankind is influencing the global climate is through carbon dioxide release from the burning of fossil fuels," Black told Exxon's Management Committee, according to a written version he recorded later.
It was July 1977 when Exxon's leaders received this blunt assessment, well before most of the world had heard of the looming climate crisis....

Climate data confirms that we are halfway towards dangerous-to-humakind  levels of global warming.

An unusually strong El-Nino has boosted global temperatures past the half way mark for dangerous climate change, according to this year's climate data.