Special counsel Robert Mueller has his next target in sight. Mueller has allegedly collected enough evidence as part of the probe into Russia’s meddling in the 2016 presidential election to file charges against former national security adviser Michael Flynn and his son, according to NBC News. Investigators on Mueller’s team will be speaking to “multiple witnesses” over the next few days “to gain more information surrounding Flynn’s lobbying work, including whether he laundered money or lied to federal agents about his overseas contacts,” NBC reports, citing “three sources familiar with the investigation.” Investigators are also looking into allegations that Flynn tried to come up with a plan to whisk a rival of Turkish President Recep Erdogan from the United States.

Mueller is pressuring Flynn to cooperate with the investigation and is apparently using the former national security adviser’s son as leverage. Flynn’s son, Michael G. Flynn, worked closely with his father and the two could be indicted at the same time. But cooperation from Flynn, who was national security adviser for only 24 days before he was fired, could help his son avoid the worst penalties.

If Mueller does charge Flynn it would be a milestone because it would mark the first time that a current or former Trump administration official would be formally charged with committing a crime. So far all those who have been charged were campaign officials.

Flynn’s son appeared to comment on the NBC report shortly after it was published. “The SJW are out in full this morning….the disappointment on your faces when I don’t go to jail will be worth all your harassment…,” he wrote on Twitter using the acronym for “social justice warriors.” Shortly afterward, Flynn’s son tweeted a 2013 photo of his father and Mueller sitting at the same table during a Senate Intelligence Committee hearing: “A picture worth a thousand words…..go nuts with your comments…”

The SJW are out in full this morning....the disappointment on your faces when I don’t go to jail will be worth all your harassment... — Michael Flynn Jr⭐️⭐️⭐️ (@mflynnJR) November 5, 2017