A former Microsoft employee who was charged with stealing gift cards and tax evasion was convicted by a jury of 18 felony counts on Tuesday.

Volodymyr Kvashuk, 25, worked as a contractor for Microsoft, then later as an employee, where he was tasked with testing the integrity of the software company’s online retail store. As part of his employment, he had access to services that generated digital gift cards for use in Microsoft’s online store, according to information published by the U.S. Department of Justice.

Kvashuk misappropriated that access to create gift cards for himself, which he later sold on the open market, prosecutors said. He used around $1.6 million to purchase an extravagant home near the company’s Redmond campus and another $160,000 to buy a Tesla, according to evidence presented in court.

As he amassed a large amount of wealth, he commandeered email accounts used by other employees and converted currency into Bitcoin in order to conceal his activities, prosecutors said. Though money entered and exited his bank accounts, he concealed the ill-gotten income from the federal government by filing false tax returns, the U.S. Attorney’s office said.

Agents with the Internal Revenue Service noticed the discrepancy, and that launched an investigation into Kvashuk’s activities, prosecutors said. He was subsequently fired from Microsoft.

At trial, Kvashuk alleged the scheme was part of his work with Microsoft and that he was “working on a special project to benefit the company,” prosecutors said.

A jury deliberated for about five hours before convicting Kvashuk on 18 felony criminal counts. All of the charges were related to financial crimes; none were related to unauthorized access to computer systems used by Microsoft.

The former employee faces up to 20 years in prison, though he’ll likely receive less prison time based on a variety of factors, including the severity of offense, financial loss and any past criminal record. He is scheduled to be sentenced in June.