A 20-year-old Massachusetts man who recently accepted a plea deal with prosecutors in Santa Clara County, California, is believed to be the first person in the US to be convicted of SIM swapping.

The SIM swapping technique allows a person to fool a mobile carrier into transferring someone else’s number to them—thus enabling possible account hijacking or other password resets that rely on the phone number itself as an authentication device. According to Vice Motherboard, which first reported the case, accused SIM swapper Joel Ortiz recently accepted a plea deal of 10 years—but it is not immediately clear which counts he pled guilty to.

Last year, Ortiz faced a 28-count indictment outlining alleged violations involving a slew of computer crimes and violations of personal identifying information law. In a police report provided to Ars, Ortiz victimized at least 22 people nationwide, including one man named Seth Shapiro, who lost $1.7 million in cryptocurrency. Ortiz is believed to have stolen a total of around $5 million using this technique.

With their success in the Ortiz case, prosecutors are continuing to investigate similar crimes. "Each arrest that we made sent shockwaves through that community," Erin West, a Santa Clara County deputy district attorney told Vice Motherboard. "That they weren’t safe in their basement, they weren't safe in their room in their mom’s house, that they were being tracked down and arrested—one by one."

West did not immediately respond to Ars' request for further comment. Ortiz will formally be sentenced at a hearing on March 14.