“I know that Donald Trump has donated over $100 million to charitable causes over the last number of years. $100 million. That’s an insane amount of money by any standard.”

That’s Trump’s former campaign manager Cory Lewandowski, speaking to CNN in March, before he was unceremoniously fired from the Trump team. It’s a figure Trump himself has bragged about repeatedly, regurgitated often when the Republican nominee comes under fire for the incompetent way he ran his businesses into the ground or his “un-PC” brand of personal attacks. When voters express concerns about giving a politically inexperienced real estate mogul with a temperament problem the keys to the White House, that $100 million in donations is a reassuring counter-balance.

The trouble is, it’s not true.

Deep investigative journalism is under-valued in the days of twitter storms and easy soundbites, but thankfully one journalist has been hot on Trump’s trail. David Fahrenthold of the Washington Post has refused to take Trump’s boasts about his charitable giving at face value.

Fahrenthold got suspicious after Trump claimed to have raised $6 million at a fundraiser for veterans in Iowa in January. But that money didn’t seem to have made it to the actual veterans. Fahrenthold started digging, and found that, while some of the money had been passed on to other charities for veterans, much of it was apparently being hoarded by Trump’s enigmatic charitable foundation: the Donald J. Trump Foundation.

Fahrenthold’s investigation into the Trump Foundation reads like a political thriller or plot-line on House of Cards. He did not take short cuts. The Washington Post made up a list of 326 charities with connections to Trump, and Fahrenthold contacted them all, asking if they ever received the personal donations that Trump claimed he made.

The answers were damning: between 2008 and May 2016, only one of those 326 charities had received a donation from Trump’s own pocket. It was worth less than $10,000.

But the real scandal of Trump’s charitable giving claims rests behind the murky front of his Foundation. Fahrenthold went through years of accounts to figure out what exactly the Foundation does, and where the money comes from. He quickly began to realise that Trump had created a reputation as a generous philanthropist by passing off other people’s donations as his own. Fahrenthold writes:

“In the Trump Foundation’s early days, between 1987 and 2006, Trump actually was its primary donor. Over that span, Trump gave his own foundation a total of $5.4 million.

His contribution shrank to $35,000 in 2007.

Then to $30,000 in 2008.

Then to $0.”

Since 2008, Donald Trump has been taking the credit for other people’s donations. One of the most vivid examples is the $150,000 donation the Trump Foundation gave to Palm Beach Police Foundation in 2010. The gift was so generous that Trump was honoured with the Palm Tree Award for his “selfless support” to the charity. In fact, every penny had come from the Charles Evans Foundation, with the Trump Foundation acting as a middle man to siphon off the glory.

Other tricks are even more legally and ethically dubious. In 2007, Trump used $20,000 from his Foundation to buy a portrait of himself at a charity auction. Fahrenthold notes that such “self-dealing” is prohibited by the IRS, but Trump does not seemed to have faced any consequences.

Trump has also recently been embroiled in a “pay-for-play” scandal, in which he is accused of donating to the Florida attorney general Pamela Bondi in exchange for political favours. In 2013, Bondi was considering whether to launch an investigation into allegations of fraud at Trump University. Trump made a donation of $25,000 to a campaign group for Bondi, and she decided to ditch the investigation. Both Bondi and Trump have stated that the donation and the investigation are unrelated, but a series of “errors” hid the donation from the IRS until it was uncovered this year. Trump has since paid a fine of $2,500 to the IRS. The initial donation to Bondi’s group came not from Trump’s own wallet, but from the Trump Foundation, violating federal rules on charities. At this point he had not contributed to the Foundation for five years.

Less sensational examples saturate Fahrenthold’s account. Many of the donations paid out by the Trump Foundation went to charities which rented Trump’s hotels and casinos for their events. In one instance, it appears that a $10,000 donation from the Foundation helped Trump persuade the charity in question to hire his winery for a fundraiser. In addition, many of the gifts Trump says he has made turn out to be corporate giveaways rather than money. Fahrenthold explains:

“Last year, the Trump campaign also put out a detailed list of what it said was $102 million in charitable giving from Trump over five years. But a close look by The Post found that not a single one of the gifts listed was actually a donation of Trump’s own money.

Most of the entries, in fact, were free rounds of golf given away by Trump’s golf courses, for local charities to auction or raffle off.”

In April, he wrote:

“The Post estimated that Trump claimed credit for at least 2,900 free rounds of golf, 175 free hotel stays, 165 free meals and 11 gift certificates to spas.”

The more Fahrenthold digs, the more damning evidence he finds. Charities that never received the gifts they were promised. Tax accounts for donations which didn’t exist. Hundreds of thousands of dollars given in Trump’s name that were in fact paid for by other people. And throughout it all, Trump’s spokespeople have tried to fudge the distinction between the Foundation and Trump himself, claiming the money paid out by the Foundation counts as a donation from Trump. It doesn’t.

Fahrenthold freely admits that he does not have all the answers, and that there may be reasonable explanations for some of these discrepancies. The easiest way to resolve these would be for Trump to release his tax returns, as virtually every presidentially nominee has done since the 1970s. Trump has refused, and no one from his campaign has been able to give any clear answers about the disturbing questions Fahrenthold raises.

But one thing is crystal clear: Trump is not being truthful about giving to charity. And if it wasn’t for David Fahrenthold of the Washington Post, he’d be getting away with it.