A Russian man who was found guilty of sneaking onto a Denmark to Los Angeles flight in November without a ticket or passport was neither the first nor the last to attempt such a scheme, a former federal security director at LAX told The Post.

Sergey Vladimirovich Ochigava, 46, was convicted last week of following another flyer through security at Copenhagen Airport, staying overnight at a terminal and sneaking onto the plane.

The suspect, who told authorities he worked as an economist, was quickly taken into custody when the plane landed in LA after officials found he did not have a passport and wasn’t listed on the passenger manifest.

He told the feds he didn’t remember how he had breached multiple levels of security and checks and balances before flying 9,000 miles across international borders.

Keith Jeffries, who served as a US Department of Homeland Security director from 2016 to 2022 and currently serves as the Vice President of K2 Security Screening Group, speculated Ochigava took his time and waited for just the right moments before making his brazen moves.

“What happens is, many people will just kind of watch and observe and see what happens, blend in with the crowd, depending on how busy it is, the security checkpoint, they’re able to navigate their way past the ticket document checker,” said Jeffries.

“The good news is that they’re screened. The aviation process is layered and if one layer fails, such as they navigate past the ticket document checker, they’re going to get screened at the checkpoint to make sure that they don’t have any prohibited items.”

Once getting through security, Ochigava clearly bode his time before sneaking onto Scandinavian Airlines Flight 931 undetected, which led the former TSA honcho to compare him to an infamous American woman who had boarded planes without credentials dozens of times over the past several decades.

“Then the next step is, if they don’t have a boarding pass, like Mr. Ochigava, and Marilyn Hartman back in the day, they’ll go to a particular gate and watch and observe, and based on the boarding process, if they can slip past the ticket agent who is checking passes while they board, they can get onto an aircraft.”

Once aboard the flight, which wasn’t completely full, Ochigava switched between unoccupied seats multiple times and chatted up passengers and the crew, whom he finessed into giving him double meal portions, prosecutors noted.

He even tried to snack on a cabin crew member’s chocolate bar, according to court documents.

His charismatic restlessness might have been a further tactic to charm flight attendants and avoid being exposed by their pre-takeoff head count, Jeffries said.

“Let’s say that layer fails, which it seems to have done so in this case, while that plane is in the air, the Customs and Border protection service, they’ve got a flight manifesto. They know who is in the air coming to the United States and they’ve got to come through customs.

“And at that point, obviously that layer caught this guy.”

Ochigava, who is facing five years in federal prison, was found to be carrying what “appeared to be Russian identification cards and an Israeli identification card,” although officials said he is not Israeli.

The man falsely claimed to have left his US passport on the plane and showed agents a photo of part of a passport that displayed his name, date of birth and identification number, but did not include a picture.

He “did not remember how he got on the plane in Copenhagen. Ochigava also would not explain how or when he got to Copenhagen or what he was doing there,” an affidavit stated.

However, the stowaway appeared to have been gallivanting around Europe without credentials for some time before heading to the US. He showed officials the most recent pictures on his phone, which included a screenshot of a map showing the location of a hostel in Kiel, Germany, and a map of an unknown city, prosecutors said.

Ochigava’s motives were not immediately clear, but his apparent methods had been seen “time and time again” by Jeffries, who noted many stowaways are clever and determined.

“I vividly remember a homeless person getting a boarding pass and trying to get to a checkpoint,” the security expert said of his time at LAX.

“They would pick up boarding passes out of a kiosk, if someone printed an extra boarding pass, they don’t have an ID, but they’ll try to use that boarding pass to try to get into a checkpoint, and sometimes they’ll navigate their way through,” Jefferies added.

“There were, from time to time, not very frequent, but we would have folks that would circumvent getting through the checkpoint to get screened and then try to board an aircraft,” he said, adding that as far as he knew, no one snuck onto a plane at LAX under his watch.

Officials are now embarking on a “very detailed” investigation to figure out how exactly Ochigava pulled it off, and who should be held accountable, Jeffries said, adding the probe’s findings would not be made public.

Copenhagen Airport confirmed as much after the Nov. 3 breach, saying in a statement it had “provided photo and video material to the authorities who are investigating the case.”

Jeffries warned that stowaways would continue to try to breach security and fly for free, and sometimes succeed, but said that there would be “less of an opportunity” for them as biometrics become more prevalent in airport security.

“He’s not the first and he’s not going to be the last.”