Follow the Sharpie: Prosecutors probing Donald Trump are sitting on 'tons' of documents bearing his handwriting, sources tell Insider

• Manhattan prosecutors have assembled a large cache of potentially damaging financial documents bearing Donald Trump's tell-tale Sharpie marks, sources tell Insider.
• Experts say handwriting on hard copy documents will be crucial to proving knowledge and intent.

Nearly three years into their investigation into Donald Trump and his company, Manhattan prosecutors have assembled a trove of potentially incriminating financial documents bearing the former president's handwritten signature, initials or other writing, Insider has learned.

The documents — marked by the bold lines of Trump's ubiquitous black Sharpie, and some in prosecutors' possession for a year or more — are evidence in an ongoing investigation into possible tax, banking and insurance fraud, according to three people directly involved in the probe.

One described these hard copy documents as extensive.

"They have a ton already that have his signature on it, that have his initials, that have his handwriting on it," said the source, who like others who spoke to Insider this week asked to not be named due to their involvement in the ongoing probe.

Depending on the amount of handwriting on them — a letter, say, as opposed to mere initials — such documents could be especially valuable to prosecutors with the Manhattan District Attorney and the New York Attorney General, which are conducting a joint criminal probe into the Trump Organization.

Handwriting signals literal, hands-on contact, making it harder for the subject of a probe to deflect personal accountability onto a company financial officer, or onto an outside accountant or assessor.

"Obviously it strengthens a case considerably when the government has documents that have been written on by the subject of an investigation," said Duncan Levin, a former prosecutor of major economic crimes who once headed the Manhattan DA's assets forfeiture bureau.

"If a jury sees someone's handwriting on a document, it does a lot to bring a document to life," added Levin.

A partner for the Manhattan firm Tucker Levin, he currently represents a cooperating witness in the DA's probe, Jennifer Weisselberg.

She is the former daughter-in-law to Allen Weisselberg, the Trump Organization CFO who is now charged with dodging income taxes by taking some of his salary in untaxed finge benefits, including tuition for his grandchildren.

Last summer, one of those tuition checks -- bearing Trump's signature in black marker -- became the first Trump-signed document publically revealed to be in the hands of Manhattan investigators from the DA's or the AG's office.

In a court filing last month, James described other potentially incriminating handwriting --including a 2011 note to Richard Byrne, CEO of frequent Trump lender Deutsche Bank, in which the AG says Trump "touted the prospects" of the Trump National Doral resort in Miami.

"Hopefully, you will be impressed!" the note read.

Trump's dealings with Deutsche Bank are a big part in the probe.

Prosecutors are looking at whether Trump fraudulently inflated his worth in securing loans from the bank, among them a $125 million loan for the Doral, one of nine Trump properties that the AG says are under investigation.

Other signed or initialed documents in probers' possession include what the AG calls Trump's "personal certifications" of his worth that have been submitted to potential lenders over the years.

A grand jury has been hearing evidence in the probe since November.

The Manhattan DA's office declined comment through a spokesperson, as did a spokesperson for the AG's office. Lawyers for Trump also declined to comment on the probe.

James' office issued her first subpoena for Trump's testimony and company financial documents back in the Summer of 2020, as part of her office's ongoing civil investigation into the business.

She complained in court papers last month that since those first subpoenas, "The Trump Organization has not made anything approaching a complete production of documents for Mr. Trump."

Hard copy documents will form the bulk of any case against the notoriously computer-averse former president, James has suggested.

"While Mr. Trump famously does not use email or a computer, at least according to reports, he regularly generated handwritten documents," she wrote in court papers filed last month.