Donald Trump
US Republican presidential candidate Donald Trump speaks during a press conference at Trump Tower.Jewel Samad/ AFP

Despite the candidate's best efforts, details in troubling lawsuits against one of Donald Trump's business enterprises have finally surfaced, raising questions about the GOP contender's integrity.

The target of two class action lawsuits and a massive fraud case brought by the New York attorney general is the now-defunct Trump University — which was not actually a university because it offered no degrees and did not have a license to operate as an educational institution.

Instead, the enterprise, which operated from 2005 to 2011, offered pricey $1,500 (£1,040) seminars on how to be successful in real estate or a "Gold Elite" package that cost $35,000 (£24,000) for workshops and some kind of mentorship.

The information is in hundreds of pages of documents in one of the federal lawsuits ordered released by Judge Gonzalo Curiel, whom Trump called a "hater" out to "railroad" him because he says the Hispanic judge wants to retaliate for the candidate's harsh words on Mexican immigrants.

Trump had hoped to stall the court cases and block information from them until after the general presidential election. But Curiel agreed with a Washington Post argument outlined in a court motion that Trump's candidacy makes his business enterprises a matter of public interest as voters consider if he has what it takes to be president.

Depositions from both clients and "university" workers call the operation a "lie," a "scheme" and a "scam." But even more damning are the release of calculating internal business "playbooks" that reveal the enterprise as part of a predatory sales strategy out to sell the priciest Trump University package to those who couldn't afford it. "We teach the technique of using OPM ... Other People's Money," note the guidelines.

"I believe that Trump University was a fraudulent scheme," sales manager Ronald Schnackenberg wrote in his testimony, "and that it preyed upon the elderly and uneducated to separate them from their money," the New York Times reports.

Hillary Clinton is using the new information to lash Trump on his university, a part of his past that the Clinton campaign believes may his greatest vulnerability.

"His own employees testified that Trump U — you can't make this up — that Trump U was a fraudulent scheme where Donald Trump enriched himself at the expense of hard working people," Clinton said at a campaign rally in New Jersey, CNN reports.

"Trump and his employees took advantage of vulnerable Americans encouraging them to max out their credit cards, empty their retirement savings, destroy their financial futures, all while making promises they knew were false from the beginning," she said. "This is just more evidence that Donald Trump himself is a fraud. He is trying to scam America the way he scammed all those people at Trump University."

Trump has denied all accusations, and claims the complaints are from a handful of cranks.