Not long before that infamous June 2016 meeting at Trump Tower between Donald Trump Jr, Jared Kushner, Paul Manafort and several Russian operatives, Don Jr. received a phone call from a blocked number. It’s long been suspected the call was from Donald Trump himself, checking to get an update on the upcoming meeting at Trump Tower, meaning that the father knew exactly why his son was setting up such an appointment.

That meeting and preceding phone call, according to former Deputy U.S. Attorney Daniel Goldman, who worked in the Southern District of New York, are all the proof Special Counsel Robert Mueller needs to prove that President Trump was engaged in a conspiracy with Russia.

During a recent appearance on MSNBC, Goldman commented:

“I bet Bob Mueller already knows because you can get the phone records from both sides. Well, he at least knows whether it’s the president or not, because you can get the number on Trump’s side, the president’s side, and you can see if there’s the call that matches up, and those phone records would have been subpoenaed early on in the investigation.”

If Don Jr. did indeed speak with his father about meeting with Russians at Trump Tower, the crimes the two can be charged with range from perjury to something much more serious, Goldman noted:

“One, Don Jr. lied to Congress, so there’s perjury right there, and, two, is that really for the first time it would place the president right in the middle of the ongoing collusion. We know certainly he learned about it after, at some point, but there has been no reporting that I’m aware of that he was aware of these efforts by — to get information from Russia that would be valuable to the campaign.”

The irony that something as simple as phone records could be what winds up bringing down Trump and members of his family is almost too perfect. They thought no one would be able to trace their actions, but they weren’t counting on a man as thorough and dogged as Robert Mueller.

Hey, Donald, the phone is ringing. It’s your attorney calling to tell you how very screwed you are.