Trump biographer calls history of president cheating people a 'target rich environment' for prosecutors

Biographer, researcher and Pulitzer Prize-winning noted that if prosecutors want to go after President Donald Trump, there's a long history of lying, cheating and scamming people.

During an MSNBC conversation Thursday, host Katy Tur described the suitcases of documents that former "fixer" Michael Cohen gave to Congress. She said that these documents are presumably incriminating for the president.

"When it comes to Donald Trump or his organization or the way he's done business over the past few decades, there's word of the New York Department of Financial Services investigating him," Tur said. "There are questions of him inflating or deflating asset in order to get favorable tax credits and insurance claims or loans."

During his testimony, Cohen revealed several possible financial crimes that could end in charges for the president. Tur asked the Trump biographer what would be the most fruitful for investigators to search through first.

Johnston explained that the financial services division is a state agency that regulates banks and insurance companies. That's where the Cohen allegations begin.

"There are so many aspects of Donald Trump cheating people, and lying to the government, and hiding records and trying to avoid audits," said Johnston. "That it is a target rich environment. It is such a rich environment, and I can't tell you which ones are going to resonate with the American public or the prosecutors find the most useful. If the state of New York decides to bring a case here, prosecutors will want to bring the most assure case they can win. Not necessarily the biggest or most important case they can file."

He went on to say that Trump has a long history of this kind of operating procedure.

"When he bought the old marineland property in Palos Verdes, California, where there's now a Trump golf course and clubhouse, part of the land is unstable," he continued. "Part of the Palos Verdes Drive is shut down all the time because it's moving. Donald was told he could not develop part of the land. Well, he, on the ground said he could not do so, made a conservation grant and took a charitable deduction for this presumably. And, yet, the land is worthless. It now has a driving range on it. So, he shouldn't be able to do that. He claimed another piece of property he said he took $100 million as a gift for land that's worth less than a tenth of that."

Watch his full take below: