Virtual private network provider PureVPN helped the FBI track down a suspected internet stalker, by combing its logs to reveal his IP address.

The US Department of Justice announced on Friday the arrest of Ryan Lin, a 24-year-old from Newtown, Massachusetts, on charges that he cyber-stalked a former roommate.

According to the complaint [PDF] against Lin in a Massachusetts District Court, his alleged campaign against Jennifer Smith included doxxing (including posting passwords to her online accounts), posting intimate photos with the suggestion they were of Smith (though without her face), rifling her personal journal and emailing private information to her contacts, posting fake profiles of her to sites “dedicated to prostitution, sexual fetishes, and other sexual encounters”, bomb threats, tricking a friend of Smith's into calling the police to her house, death and rape threats, and sending “images that likely constitute child pornography” to her family and friends.

The Feds allege Lin used various privacy services: logging in via Tor, to conceal his IP address; VPN services; anonymised international texting services; and offshore private email providers.

However, the complaint claims, he made a fundamental error by using a work computer for some of his campaign, and even though he'd been terminated and the OS reinstalled on the machine, there were footprints left behind for investigators to associate Lin with the 16-month campaign against Smith.

Key details turned up by investigators included:

Lin's most-visited Website was the TextNow anonymous texting service;

Lin had a Proton Mail account;

There were “artefacts” indicating he used PureVPN; and

Similar artefacts suggesting he'd accessed his Gmail account from the machine.

“Further, records from PureVPN show that the same email accounts – Lin's Gmail account and the teleprtfx Gmail account – were accessed from the same WANSecurity IP address,” the document stated.

And that's where the surprise came in – at least for those who believed a VPN is a complete protection: “Significantly, PureVPN was able to determine that their service was accessed by the same customer from two originating IP addresses,” claim the Feds (allegedly, those IP addresses were at Lin's work and home addresses).

The investigators claim that tweets from Lin showed he was aware there was some risk of logging from VPN providers. As recently as June, he posted a tweet critical of provider IPVanish about its logging claims:

“There is no such thing as a VPN that doesn't keep logs. If they can limit your connections or track bandwidth usage, they keep logs.”

If found guilty, Lin faces up to five years in prison and up to three years of supervised release.

Pure VPN's privacy policy states: "We will only share information with authorities having valid subpoenas, warrants [and] other legal documents...provided we have the record of any such activity.

®