A man who advertised and sold the notorious StealthGenie mobile-phone spyware has pleaded guilty to federal charges, earning himself a $500,000 fine, the Department of Justice said Tuesday. Hammad Akbar, a Danish citizen originally from Pakistan, was arrested in September and charged with advertisement and sale of interception devices — a category that includes spyware apps like StealthGenie. Once the app was secretly installed on the target phone, it would remain undetectable while recording every phone call and text, every photo and every email, among other things. The app, which investigators said was designed for use by “stalkers and domestic abusers,” could be installed on iOS, Android and BlackBerry devices. “This illegal spyware provides individuals with an option to track a person’s every move without their knowledge,” the FBI’s Andrew McCabe said.

Akbar allegedly sold a copy to an undercover agent in late 2012, which enabled the FBI to swoop in. His site was shut down immediately, and he confessed to the crimes shortly thereafter, prosecutors said. He was sentenced to time served, fined half a million dollars and ordered to forfeit the source code of StealthGenie to the government. It was the first-ever criminal conviction criminal conviction involving the advertisement and sale of a mobile device spyware app, the Justice Department said.

The 31-year-old Akbar, of Lahore, Pakistan, was arrested in September in Los Angeles and prosecuted in federal court in the Eastern District of Virginia. StealthGenie was hosted from a data center in Ashburn, Virginia. The case was investigated by the FBI’s Washington Field Office.