Authorities in the United States have reviewed airport security footage as they continue to investigate how a woman sneaked on board a Delta Air Lines flight from New York to Paris without a ticket last Tuesday –– one of the busiest travel days of the year.

Inspectors from the Transportation Security Administration are preparing a civil case against the stowaway after reviewing airport security video from inside John F. Kennedy International Airport, agency spokesperson Alexa Lopez told CNN.

The stowaway initially slipped past facial recognition ID scanners at the TSA checkpoint undetected, the TSA said, though she did go through baggage screening where officers found two bottles of water.

“The TSA will open civil cases against passengers when there’s evidence that procedures may have been violated,” Lopez said. The TSA cannot bring criminal charges, though it can refer them to the Justice Department.

A Paris airport official identified the female stowaway as a 57-year-old Russian national.

The passenger – whom French officials are trying to return to the U.S. – remains in custody in France. She was scheduled to take a return flight to the United States Saturday afternoon but French authorities had to remove her from the aircraft  after she started screaming, according to the Paris airport official.

The pilot refused to take her because she was too unruly, the official told CNN Monday.

French border police brought the passenger back to a waiting zone at Charles de Gaulle Airport for people awaiting deportation. She can be held in the zone, known as ZAPI, for up to 20 days.

French authorities want her to return to the United States of her own volition. But failing that, they will force her to go back with an escort, in formal custody.

Since arriving in Paris, she has been evaluated by a doctor.

Inspectors from the TSA are planning to meet the stowaway at JFK when she returns to the States, Lopez said.

The TSA says the incident shows electronic gate technology – known as e-gates, which could integrate with the agency’s facial recognition systems at checkpoints – could prevent incidents like this, though it would require more federal investment.

What remains a mystery is how the person was able to slip past Delta gate agents at JFK. A source familiar with the incident said the stowaway was able to evade detection by the flight crew on the plane because the flight was not full, though passengers told CNN the woman was able to hide by moving between bathrooms.

Delta has not said how she was able to make it onto the plane once she made it past the TSA checkpoint.

The airline says it is conducting an exhaustive investigation of what may have occurred, but declined further comment.

Incidents like these do happen, but not frequently, according to former Department of Homeland Security official Keith Jeffries, who was federal security director when he left DHS in 2022.

In about 20 years working with DHS and the TSA, Jeffries estimated, he saw similar situations play out about 30 times.

Airlines are adding more technology to their boarding process to prevent these lapses, said Jeffries, now vice president of K2 Security Screening Group, an aviation security firm. But things still happen, especially during peak travel periods.

The public can also help keep the skies safe during the busy travel season, he said.

As simplistic as it sounds, if you see something, say something, Jeffries said. One of the most important layers of the entire security process is the public themselves.