In a flood of emails and snail-mail letters come to light as a result of the Sierra Club’s Freedom of Information Act requests, EPA Administrator Scott Pruitt’s close relationships with many leaders of the industries his agency is tasked with regulating became evident.

In a detailed Sunday Washington Post report, multiple examples are revealed of industry officials asking for relaxed regulation and soon after getting corresponding rollbacks.

In addition, published in a string of tweets by a New York Times reporter, many old fashioned letters also show Pruitt’s propensity for rubbing shoulders with industry bigwigs. The thank you notes to oil and gas executives often feature handwritten scrawling from Pruitt in the corners.

On Saturday, news broke that the EPA’s chief ethics official is calling for multiple investigations into Pruitt’s conduct as head of the agency.