Trump CFO Allen Weisselberg told a blatant lie about a blatant lie. Here's how NYC prosecutors got him for perjury.

• On Monday in Manhattan, Allen Weisselberg pleaded guilty to two state felony counts of perjury.
• Both lies involved the size of Donald Trump's Trump Tower penthouse on Fifth Avenue in Manhattan.

Allen Weisselberg had little choice but to plead guilty to perjury after Manhattan prosecutors caught him blatantly lying about lying, as they disclosed in court on Monday.

And underlying this stack of lies is Donald Trump's obsession with pretending to banks that he had a massive, gigantic, colossal penthouse — the most expensive apartment, he claimed a decade ago, in New York City history.

Here's how Weisselberg, an ever-loyal former Trump Organization chief financial officer, was inescapably caught telling easily provable lies about that penthouse during sworn testimony — felonies that are now set to send him back to jail for up to five months.

It started in 2012

It was in 2012 that Trump was first recorded — in official net-worth statements — wildly exaggerating the size of his penthouse apartment, which spanned three floors atop Trump Tower on Manhattan's Fifth Avenue.

Trump knew his penthouse was 10,996 square feet. He'd signed a real-estate record attesting to that size in 1994.

But in the five years of annual net-worth statements he issued for the years 2012 through 2016, he claimed the apartment was 30,000 square feet.

"A discrepancy of this order of magnitude, by a real estate developer sizing up his own living space of decades, can only be considered fraud," the judge of Trump's civil fraud trial, state Supreme Court Justice Arthur Engoron, wrote back in September.

"Absurd," the New York attorney general called Trump's claim in his 2015 net-worth statement that the apartment, which was 30 years old, was worth $327 million.

She noted that by 2015, no apartment in the city, not even newer and larger ones, had sold for anywhere near that princely sum.

In 2015, Trump told a Forbes reporter his triplex was 30,000 square feet, the AG said in court documents released Monday.

Weisselberg was present at that audio-recorded interview with Forbes, the documents said.

But in a pretrial deposition conducted in 2020 by the state district attorney's office, Weisselberg denied ever being in the same room as Trump when the triplex's size was discussed, the assistant Manhattan district attorney Gary Fishman said Monday, during the ex-CFO's plea hearing.

Weisselberg was asked this question at the 2020 deposition: "Were you ever present when Mr. Trump described the size of his triplex?"

"No," Weisselberg answered.

Weisselberg's denial could have protected not only himself but also Trump — if only it had been true.

On Monday, Weisselberg admitted this inescapable deposition falsehood — one that prosecutors may have easily verified with Forbes, which reported that Trump and Weisselberg were together at the 2015 interview about the size of the triplex.

Weisselberg also admitted Monday that he'd lied in the same 2020 AG deposition about the timing of when he knew the 30,000-square-foot valuation was wrong.

"We didn't find out about the error until the Forbes article came out," Weisselberg swore under oath, despite the earlier sit-down and extensive pre-story emails between Forbes and Weisselberg concerning the square-footage flub.

Engoron and state officials have contended the square footage was intentionally inflated by Trump and Weisselberg as far back as 2012.

They cite a February 2, 2012, internal Trump Organization email as proof. Officials noted Monday that Weisselberg was cc'd on the email, which included as an attachment the 1994 real-estate record signed by Trump that indicated the triplex was 10,996 square feet.

Read the charges Weisselberg pleaded guilty to here.

Four days after learning Forbes was publishing a bombshell — "Donald Trump has been lying about the size of his penthouse" —Trump went ahead and issued his 2016 net-worth statement anyway, claiming the apartment was 30,000 square feet one last time, according to fraud-trial evidence.

Weisselberg's career as a loyal Trump witness now appears to be over

The last Manhattan jury to hear Weisselberg testify didn't believe him. In finding the Trump Org guilty of dodging payroll taxes, they rejected the ex-CFO's claims that in running the scheme he'd had purely selfish motives and that those at the top of the ladder — Donald Trump and his two eldest sons — had nothing to do with it.

Weisselberg could have been a key prosecution witness again later this month in Trump's coming hush-money trial.

That's the Manhattan criminal trial in which Trump faces anywhere from zero to four years in prison if he's found guilty of lying in business documents to hide a $130,000 hush-money payment to the porn actor Stormy Daniels days before the 2020 election.

But Monday's perjury plea doesn't require Weisselberg to cooperate in any way with prosecutors. Instead, Weisselberg's only obligation between now and sentencing is to remain law-abiding and not flee the jurisdiction, or else he'll face up to seven years in prison.

And prosecutors have already said they don't plan to call Weisselberg as a witness, despite the former CFO's role in the paperwork underlying the hush-money payment and its accused cover-up.

It's unclear what help, if any, Weisselberg could have been as a hush-money defense witness. The alleged fraud's underlying documents say what they say, and no testimony could change their contents.

But now, given his official history of lying under oath on Trump's behalf, it's unlikely Trump's side would ever call Weisselberg to the stand, either.

Jury selection in the hush-money trial is scheduled to begin March 25, with the trial expected to last six weeks.