New facial recognition tech at an airport near Washington, DC caught a man attempting to enter the US with false documents, the US Customs and Border Protection said yesterday.

While arriving in Washington Dulles International Airport after a flight from São Paulo, the man presented a genuine French passport as his ID. But the facial recognition system flagged the man’s face as not matching the passport photo. Officers then searched his person, as he grew “visibly nervous,” and found his real ID card from the Republic of Congo in his shoe.

The man left the US after the US attorney’s office decided not to prosecute him.

The system had just been installed on Monday, so this was the first instance where it caught a person illegally entering the US. There are a total of 14 airports using the facial recognition technology to screen out people arriving in the US with false documents.

Dulles Airport has been testing facial recognition systems since 2015, while New York’s JFK Airport started to test the technology in 2016. Both airports are part of the broader biometric exit pilot that uses facial recognition to identify visa holders as they exit the country.

Customs and Border Protection is still assessing whether travelers in the future could use biometrics to verify their identities instead of presenting boarding passes and ID documents, the agency said in a statement.