A woman who was arrested at Dulles International Airport last week with more than seven kilograms of heroin in her suitcase said she was sent from Mexico by unknown individuals and was watched throughout her flight, federal agents said.

Nelly Davila is charged in Alexandria federal court with importing heroin, facing a mandatory minimum of five years in prison.

Authorities said Davila was stopped by a customs agent at the airport’s international baggage claim after a Friday flight from Mexico City. She told them she was visiting friends she had met in California, but she could not name the hotel where she would be staying.

When Davila’s luggage was searched, authorities said, security agents found 7,785 grams of a substance that tested positive for heroin.

One kilo of heroin can sell for about $80,000 to suppliers in the United States and about $300,000 on the street, according to authorities. Mexican drug cartels have largely taken over the heroin trade in the United States, with higher-quality narcotics and a sophisticated distribution network.

Davila told the agents she had taken a plane earlier that week from Hermosillo, Mexico, to Mexico City with individuals she could not name, then taken to a bodega in nearby Cuemavaca, authorities said. She said she spent two days at the Hotel Azul Turquesa in Mexico City, waiting for the drugs to be prepared.

She was then driven to the airport, where the drugs were put in her luggage, agents said. She said she was told she would be watched on her flight and that an unidentified man approached her at the airport and asked about her seat assignment, authorities said.

When Davila got to the United States, the agents said, she told them she was to go to a nearby hotel to deliver the package and be paid.