Two Maryland residents were found guilty of trying to defraud Apple out of millions of dollars with fake iPhones from China on Tuesday, according to the U.S. Department of Justice.

Haotian Sun and Pengfei Xue, both Chinese nationals that were residing in Germantown, Maryland, were charged with mail fraud in a U.S. District Court after trying to exchange counterfeit phones for real iPhones from Apple retail stories and service providers, according to a news release from the U.S. Department of Justice.

The two 33-year-olds received shipments of inauthentic iPhones from Hong Kong at mailboxes throughout the D.C. area, according to government evidence. They then tried to tried to submit the phones with fake serial numbers for repairs at local Apple stores, including the Apple Store in Georgetown.

The investigation found that Sun and Xue submitted more than 5,000 fake iPhones to Apple for exchanges during their mail fraud scheme, which would have cost the tech developer more than $3 million.

Officials said Sun and Xue used many aliases during the scheme and were arrested on Dec. 5, 2019. They could face up to 20 years in prison.

Their sentencing is scheduled for June 21.

Homeland Security Investigations and U.S. Postal Inspection Services investigated this case.