"On February 13, 2023, it came to the Government’s attention, based on data obtained through the use of a pen register on the defendant’s Gmail account, that the defendant has used a VPN or “Virtual Private Network” on at least two occasions to access the internet."
I hadn't heard of a pen register before. Apparently it's monitoring:
- All email header information other than the subject line
- The email addresses of the people to whom an email was sent
- The email addresses of people whom received the email
- The time each email is sent or received
- The size of each email that is sent or received
As an aside, would headers give away the fact he was using a VPN when using Gmail?