By Saskya Vandoorne, Mark Morales, Holmes Lybrand, Brynn Gingras and Lex Harvey, CNN

(CNN) — The extraordinary journey of a stowaway who made it all the way to Paris on a Delta Air Lines flight from New York last week has alarmed both aviation experts and travelers.

Russian national Svetlana Dali, 57, was identified as the rogue passenger, according to French authorities. She was arrested by the FBI Wednesday upon her deportation to the US. Her initial court appearance is due Thursday, the US Attorney’s Office for the Eastern District of New York said.

Dali is expected to be charged with being a stowaway on a vessel or aircraft without consent and could face up to five years in prison.

As her case raises serious questions about airport security, here’s what we know:

What happened?

Dali snuck onto Delta flight 264 from New York’s JFK International Airport to Paris Charles de Gaulle Airport on November 26.

Attempting to stay undiscovered, she hid in the bathroom to remain out of the crew’s sight, according to one passenger account.

“I overheard the flight attendants talking about it with the pilots,” New York City real estate broker Rob Jackson told CNN. “They said this person was in one lavatory and then would exit and walk to a different lavatory and go in there for a long time.”

Crew members did not alert passengers to the stowaway in their midst until the flight landed in the French capital, Jackson said.

“The first announcement to passengers that there was a problem was when we parked at the gate and they instructed us all to remain seated because French police were going to board the aircraft to deal with ‘a serious security issue,’” he said.

In a video recorded by Jackson, a voice on the plane’s intercom says, “Folks, this is the captain, we are just waiting for the police to come on board. They may be here now and they directed us to keep everyone on the airplane until we sort out the extra passenger that’s on the plane.”

Dali was detained by French police, who found she was ineligible to enter the country and ordered her to be sent back to the US.

Who is Svetlana Dali and what do we know about her?

Records indicate Dali once lived in the Philadelphia area.

Authorities have not said whether she had tried to sneak onto a plane before, or if she was previously known to law enforcement. It is unclear how long she had been in the United States.

Dali has filed two lawsuits in recent months alleging that she is the victim of military-grade chemical weapons and a kidnapping plot, according to court records.

She had applied for asylum in France a few years ago, a Paris airport official told CNN.

Following her detention at the Paris airport, she was scheduled to return to the US on Saturday – but was removed from a Delta flight to New York after creating a disturbance before takeoff.

She eventually took off on Wednesday. Wearing a black jacket, pale gray beanie and a pink scarf, Dali sat quietly in the middle aisle at the back of the plane, flanked by two French security officials.

During the flight, she occasionally leaned her head against the seat in front of her and stared at the floor or closed her eyes and listened to music.

Dali declined to speak with CNN after landing.

CNN has attempted to contact Dali’s family and friends to find out more about her.

How did she get past security?

Dali bypassed an employee in charge of the Known Crewmember checkpoint at JFK Terminal 4, then got through checkpoints where her ID and boarding pass should have been verified, a Transportation Security Administration spokesperson told CNN.

At the gate, she placed herself in the middle of what appeared to be a family traveling together, according to a senior law enforcement official briefed on the investigation. She was not carrying any prohibited items, according to a TSA spokesperson.

Asked repeatedly to describe what took place at the gate, Delta has not commented.

The airline said it had reviewed its own security after the incident and insisted its infrastructure “is sound.”

Delta blamed the breach on a “deviation from standard procedures,” but did not specify how it strayed from its usual security practices.

“We are thoroughly addressing this matter and will continue to work closely with our regulators, law enforcement and other relevant stakeholders,” Delta said in a statement. “Nothing is of greater importance than safety and security.”

CNN has reached out to Delta to ask whether Dali will be banned by the airline.

TSA inspectors are also preparing a civil case against Dali after reviewing security video from inside JFK Airport, an agency spokesperson told CNN. The TSA cannot bring criminal charges, though it can refer them to the Justice Department.

The incident should serve as a “wake-up call” for the airline industry, according to a CNN aviation analyst.

Mary Schiavo, a former inspector general for the US Department of Transportation, said, “It’s a really big deal and it leaves our vulnerabilities exposed to the world.”

CNN’s Chris Boyette, Ray Sanchez, Pete Muntean, Alexandra Skores, Rebekah Riess, Holmes Lybrand, John Miller, Taylor Romine and Amanda Jackson contributed to this report.