State prosecutors in New York are using Michael Cohen's congressional testimony to guide them as they investigate whether President Donald Trump committed a variety of financial crimes as he built his vast real-estate empire.

The Washington Post on Thursday published a lengthy look at how Trump went about inflating and deflating the value of his assets for insurance and tax purposes.

After Cohen testified to Congress, New York authorities and congressional investigators sent subpoenas and document requests to Trump's insurance provider, financial institutions, and more.

Meanwhile, federal prosecutors in the New York City boroughs of Manhattan and Brooklyn are known to be investigating Trump's business dealings before the election and his inaugural committee, respectively.

New York law is known to be tough on financial crime, and experts say the state probe — not the Russia investigation — poses the greatest legal threat to Trump's businesses and his presidency.

New York state prosecutors are using Michael Cohen's testimony to the House Oversight Committee to point them in the right direction as they investigate President Donald Trump's sprawling real-estate empire, business dealings, and finances.

Cohen, Trump's former longtime lawyer and fixer, appeared before the committee in an open hearing last month, where he called the president a "cheat" and a "con man," and said he was involved in wrongdoing or criminal conduct.

Among other things, Cohen told the committee that Trump had inflated his assets for insurance purposes and deflated them for tax purposes.

"Who else knows that the president did this?" Rep. Alexandria Ocasio-Cortez, who questioned Cohen extensively about Trump's finances, asked him.

"Allen Weisselberg, Ron Lieberman, and Matthew Calamari," Cohen answered.

"And where would the committee find more information on this?" Ocasio-Cortez asked. "Do you think we need to review his financial statements and his tax returns in order to compare them?"

"Yes, and you'd find it at the Trump Org.," Cohen said, referring to the Trump Organization.

Read more: The 8 biggest takeaways from Michael Cohen's blockbuster testimony against Trump

New York prosecutors follow Cohen's breadcrumbs

Michael Cohen. AP Photo/Julie Jacobson

It looks like New York authorities — as well as congressional investigators — took Cohen's cues, according to The Washington Post, which on Thursday published a detailed look at how Trump inflated his assets and net worth to authorities and investors.

On Wednesday, the House Oversight Committee announced that it had requested 10 years of Trump's financial statements from his accounting firm, Mazars USA. The Post reported that the committee also asked Mazars for supporting documents used to produce those statements, as well as communications between the firm and Trump.

Meanwhile, earlier this month, the New York State Department of Financial Services subpoenaed records from Aon, Trump's longtime insurance company.

A person with knowledge of the subpoena told USA Today the request sought records of communications involving Aon, Trump, and his company, as well as internal documents for related insurance coverage.

The New York state attorney general's office has also subpoenaed Deutsche Bank, which Cohen said received financial statements from Trump that misrepresented his assets.

Read more: Prosecutors left a trail of breadcrumbs about Trump's finances, and House Democrats are now digging deeper

Trump's financial worth has perhaps been the biggest question mark looming over his real-estate career.

In 2009, he told The Wall Street Journal he was worth $5 billion, not including the value of the Trump brand. A month later, Trump's accountant prepared a financial statement that said his net worth was "in excess of $3 billion." Two years later, Trump bragged during a Comedy Central roast that he was worth more than $7 billion. In May 2016, at the height of that year's presidential election, Trump said in a press release that he was worth more than $10 billion.

The president has admitted that the statements he makes about his financial worth are not always based in fact.

In 2007, Trump sued the journalist Timothy O'Brien after O'Brien wrote in his book "TrumpNation: The Art of Being the Donald" that Trump's actual net worth was between $150 million and $250 million.

In a deposition Trump gave for the lawsuit — which was eventually dismissed — he acknowledged that his net worth fluctuated based on his emotions.

Read more: Here's a glimpse at Trump's decades-long history of business ties to Russia

It's not uncommon for real-estate businessmen to exaggerate their net worths. The problem arises when one inflates or deflates their net worth, or makes false representations about their financial stability, in order to mislead potential investors and authorities.

Accountants reportedly did not verify the figures Trump gave them for his financial statements

According to The Post, when Mazars USA was putting together statements of Trump's financial stability, accountants at the firm did not verify the figures Trump provided to them, saying that it was not their job to check for their authenticity.

When asked if the values provided "have to be logical," one of the accountants replied, "The value per se does not have to be logical."

Trump is weathering at least 16 known investigations into his finances, his business, his inaugural committee, his campaign, and more.

For a long time, it seemed like the special counsel Robert Mueller's Russia investigation — which examined whether members of the Trump campaign conspired with Russia during the 2016 election and whether Trump obstructed justice — posed the greatest legal threat to the president and those around him.

But over the last several months, state and federal prosecutors in New York have emerged as a bigger risk.

Investigators in the Southern District of New York (SDNY) are delving into Trump's business dealings before the election, centering around hush-money payments that Cohen facilitated to women who said they had affairs with Trump.

Read more: New York state prosecutors indict Manafort on new charges just minutes after he was sentenced to 7 1/2 years in prison in the Mueller probe

Cohen pleaded guilty to tax evasion, bank fraud, and campaign-finance violations as part of that investigation. In their charging document, prosecutors wrote that Cohen admitted to breaking election law at the request and direction of "Individual-1," who is widely believed to be Trump. Cohen's allegations make Trump an unindicted coconspirator in the SDNY's investigation, legal experts say.

Demanding records from Trump's inauguration committee

Recently, the SDNY also recently subpoenaed the Trump inaugural committee for documents related to its finances. The subpoena came from the office's public corruption unit, ABC News reported.

Meanwhile, the US attorney's office in Brooklyn, New York, is conducting a separate investigation into possible illegal donations made by foreign entities.

And Cohen told the House Oversight Committee the SDNY is investigating "wrongdoing or illegal acts" involving Trump that have not yet been publicly revealed.

Getty Images / Paul Morigi

Trump's alleged financial misconduct in New York 'could be what actually sinks the big ship'

New York also has jurisdiction over the linchpin to Trump's success: his businesses.

The Trump campaign, moreover, is headquartered at Trump Tower in Manhattan, New York, and state investigators have cited that as a key reason they want to obtain a full, unredacted copy of Mueller's report in the Russia investigation. Specifically, they believe the document could contain evidence of criminal wrongdoing that could be subject to state charges against Trump or people in his orbit, such as his children and other family members.

New York authorities, as well as the state's law, are also known to be tough on financial crime.

"Fraud cases are the linchpin of what most attorneys general do, and the laws are particularly strong in New York," Paul Nolette, a political-science professor at Marquette University who studies attorneys general, told FiveThirtyEight in January.

"The Mueller investigation is the shiny object everyone is watching," Berit Berger, a former federal prosecutor and the executive director of Columbia Law School's Center for the Advancement of Public Integrity, told the outlet. "But under everyone's nose are what look like much more straightforward violations of state law, including some pretty flagrant tax fraud. Depending on what happens with Mueller, that could be what actually sinks the big ship."

It's not just Trump who could face legal jeopardy in his home state.

People who are convicted of state crimes cannot be pardoned, and Trump's children, other family members, and campaign associates may also see trouble ahead, as Paul Manafort, Trump's former campaign manager, found out earlier this month.

Just minutes after Manafort was sentenced to 7 1/2 years in federal prison as a result of the Mueller probe, state prosecutors in New York slapped him with a 16-count indictment accusing him of engaging in a yearlong fraud scheme to falsify business records and illegally obtain millions of dollars in loans.