It’s getting increasingly harder for Michigan officials to claim ignorance about the poisoning of the city of Flint.

According to newly revealed emails, an aide to Governor Rick Snyder learned nine months ago of an outbreak of Legionnaire’s disease tied to Flint’s water supply. Ten people died from the bacterial infection, which Snyder made public in mid-January. At the time, he said he’d only become aware of the outbreak a couple days earlier. The emails don’t prove that’s false, but they shows that Snyder probably should have known about it.

“The increase of the illnesses closely corresponds with the timeframe of the switch to the Flint River water. The majority of the cases reside or have an association with the city,” a Genesee County health official wrote to the state Department of Environmental Quality and to Flint’s state-appointed emergency manager on March 10. “This situation has been explicitly explained to MDEQ and many of the city’s officials … I want to make sure in writing that there are no misunderstandings regarding this significant and urgent public health issue.”

Three days later, DEQ’s spokesman, Brad Wurfel, wrote to DEQ Director Dan Wyant as well as to a Snyder aide, noting the Genesee county official had “made the leap formally in his e-mail that the uptick in cases is directly attributable to the river as a drinking water source,” which Wurfel called “beyond irresponsible.”