WASHINGTON — The mystery of whether Prince Harry fibbed on his immigration papers will likely remain unsolved, as a pair of federal court cases seeking to compel disclosures about the terms of his visa stalled in the months before he and wife Meghan Markle announced Wednesday they would be returning to the UK.

Lawyers at the conservative Heritage Foundation sued the Department of Homeland Security and the State Department in 2023 to crack open the Duke of Sussex’s immigration file after Harry admitted in his memoir “Spare” to taking drugs.

Upon emigrating to the US in 2020, the black sheep royal should have disclosed his substance abuse — including dabbling in cocaine, cannabis, and psychedelic mushrooms — in a document that would have made its way to DHS.

The now-41-year-old’s visa application to the State Department would have also been fraudulent if Harry didn’t share his youthful misadventures with drugs.

But Heritage’s Freedom of Information Act lawsuits failed to bring forward information from either agency about the prince’s immigration status before the duke and duchess announced they would be crossing back over the pond six years after stepping back from royal duties.

“We still want all the documents,” said former Heritage staffer Mike Howell, now president of the government accountability group Oversight Project and a party to the lawsuits.

“Prince Harry may be leaving, but our fight for the truth goes on,” Howell added. “Maybe he won’t be able to come back.”

President Trump had ruled out deporting the prince early in his second term, joking to The Post’s Miranda Devine: “I’ll leave him alone. He’s got enough problems with his wife.”

A well-placed DC source claimed that while the legal battles challenged Harry and Meghan’s presence in the US, the couple was really forced to exit after what this person called their “grift” — including an ill-fated bid to become Netflix stars and Meghan’s attempt to carve out a Martha Stewart-esque niche as a lifestyle brand — ran out of steam.

“Spare” broke records by becoming the fastest-selling nonfiction book of all time when it was published in January 2023.

In March 2025, the Heritage suit against DHS yielded a handful of heavily redacted court declarations from federal agents who had personally reviewed Harry’s immigration file.

The agency only confirmed that it held “entry and exit records to the United States” for Harry but declined to discuss other documents due to “the Duke’s right to privacy.”

A federal judge had already ruled out releasing information from the file itself, writing in a September 2024 opinion that “the public does not have a strong interest in disclosure of the duke’s immigration records.”

An earlier declaration by a DHS Freedom of Information Act officer claimed that the public also wasn’t entitled to the records if their release could submit Harry to “harm” or “harassment.”

Heritage attorneys subsequently sued the State Department for a broader range of documents that amounted to all records on the royal since January 2020.

Department officials revealed in late July that just 18 records were responsive to the initial request but would all be withheld due to FOIA and immigration laws.

Heritage lawyers theorized that Harry likely came to the US on a so-called O-1 visa, which is reserved for people “of exceptional talent or ability.”

To obtain an O-1 visa, applicants must provide a petition from a sponsor with evidence of “exceptional talent or ability.” In Harry’s case, attorney Samuel Dewey previously told The Post, that sponsor could have been one of the prince’s foundations and the visa may have been granted based on his “fundraising” prowess or any other skill deemed “exceptional.”

Both suits were also filed under suspicion that Harry may have received special treatment from the feds, regardless of how truthful he was about his confessed drug use.

Reps for DHS and the State Department did not respond to requests for comment.