After he stopped, the complaint says, the teen told a United flight attendant what happened and asked to be moved to another seat.

Once the flight from Seattle landed at Newark Liberty International Airport, the girl called her parents.

While she did, the man left the airport, Johnny McCray, an attorney for the girl’s family, told The Washington Post.

The incident last week angered the girl’s family, who questioned why United allowed the man to leave the plane and the airport after he’d been accused of a crime.

The FBI, which has jurisdiction over incidents during air travel, was contacted to take over the criminal investigation. Investigators were later able to get a flight manifest to determine the name of the passenger seated next to the girl. The teen picked a 28-year-old man named Vijakumar Krishnappa out of a photo lineup, said McCray.

A complaint describing the charge against Krishnappa and what witnesses said happened was filed in federal court in New Jersey on July 24, the day after the incident. Court records show he was arrested and charged with knowingly engaging in sexual contact with a minor female on the same day.

Krishnappa has been released on bond, placed on electronic monitoring, and ordered to not have any contact with minors while the criminal case is pending, according to court records.

His court-appointed attorney, John Yauch, said his client “adamantly denies the charges and deserves to be considered an innocent man.” Yauch declined further comment.

Krishnappa is in the United States for a months-long medical fellowship, which allows foreign doctors to come to the country and learn from experts here, according to information provided by the girl’s mother. It’s unclear what his country of origin is.

The teen, who is from Washington state, was headed to Princeton University to take part in a leadership program, her family said. (The Post’s policy is not to identify victims of alleged sex crimes.)

Her mother said the girl’s proximity to Krishnappa, who has a New York City address, worries her despite the court order preventing him from having any contact with the teen.

“This is such a horrific and despicable act on his part,” McCray said of Krishnappa. “And for him to be a doctor … it’s concerning.”

While the Federal Aviation Administration has policies on how to deal with unruly passengers and other incidents that involve flight safety, what happens to a person accused of a crime after a plane lands is up to law enforcement.

A spokesman for the federal agency said flight crews regularly notify law enforcement before landing about a wide variety of incidents that occur on the aircraft. Whether that happened in the teen’s case is unclear.

The Post sent United an email asking for information about the incident — including what happened after the plane landed in New Jersey, and what the airline’s policy is when a passenger reports an incident during air travel. A United spokeswoman responded with a brief statement, saying: “The safety and security of our customers is our top priority. We take these allegations seriously and continue to work closely with the proper authorities as part of their review.”

The allegations against Krishnappa and criticisms of the airline’s handling of the incident come just months after United found itself in the middle of a public relations fiasco involving viral videos of a passenger getting dragged off a flight. The April incident resulted in apologies from United’s chief executive to the passenger, David Dao.

The airline has since been embroiled in numerous incidents reported in the media.

Watch more!

United was accused later in April of forcing a couple off a flight while on the way to their own wedding. A United spokeswoman said the couple “repeatedly attempted” to sit in upgraded seating they didn’t pay for.

In May, an emergency-room nurse with an overactive bladder said flight attendants prevented her from using the bathroom and forced her to urinate in a cup during a Mesa Airlines flight from Houston to Kansas City. Mesa Airlines is a regional carrier operating as United Express.

In June, United apologized after a two-year-old video surfaced showing an employee pushing an elderly passenger to the floor during an argument over a ticket.

And in July, a mother was forced to give up her 2-year-old son’s seat and hold the child throughout their flight after an adult passenger somehow ended up with the same seat number as the toddler. That same month, rapper ScHoolboy Q accused United of mistakenly sending his dog on the wrong plane and to the wrong city.

Watch more!

Avi Selk, Samantha Schmidt and Peter Holley contributed to this story.