Allegations that ExxonMobil purposefully promoted climate change denial despite knowing from their own research of the reality of climate change, are snowballing: This past Friday, four members of Congress sent a letter to the Securities and Exchange Commission, citing investigative efforts by InsideClimate News and The Los Angeles Times as basis for a demand that the SEC investigates whether ExxonMobil violated security laws because they failed to tell investors about the dangers of climate change.

These investigations, they write, “suggest that top executives at Exxon embarked on a massive campaign of denial and disinformation after company scientists connected the burning of fossil fuels with global warming.”

It’s been alleged since July 2015 that ExxonMobil knew of the connection between fossil fuels and climate change, but continued to fund climate change groups. Between 1977 and 1986, the company’s team of scientists were considered the global experts on climate change and had already begun to warn management that the warming of the planet via the use of fossil fuels could endanger it.

But by the 1990’s, ExxonMobil was taking out ads in prominent newspapers contending that climate change science was uncertain and funneling cash into anti-climate change policy groups.

Since the news broke this summer by The Guardian, more and more people have demanded for transparency from the oil and gas company, fueled by the long-form investigative work by InsideClimate News and the LA Times this fall. Major Democratic players like Bernie Sanders, Elizabeth Warren, and Martin O’Malley have called for a federal investigation into ExxonMobil. When asked last week by 350 Action if the Department of Justice should investigate, Hillary Clinton replied that they should.

Meanwhile, ExxonMobil’s Ken Cohen has been posting a series of self-righteous blog posts on the company’s blog “Perspectives,” the most recent beginning with the oh-so-weary title, “Here we go again. . .”. Cohen has argued from the start that claims that ExxonMobil has contributed to the denial of climate change are false. A series of back-and-forth between Cohen and InsideClimate News has ensued, with the Pulitzer-Prize winning news organization arguing that Cohen’s use of graphs is inaccurate at best, purposefully misleading at worst.

It hasn’t been announced yet whether ExxonMobil will face a federal investigation. But the eyes of major players are now watching, and regretting, that they didn’t take action earlier.

Photos via David McNew/Getty Images