Before Donald Trump was the Republican nomination for president, he charged thousands of dollars for an education at "Trump University," promising to share the secrets of his real estate investing success.

The only problem: Trump University wasn't anything close to a university. It was a multilevel marketing scheme.

Students were lured in with a free 90-minute seminar. Trump University promised that the real insider knowledge, and even access to Trump himself, could be theirs if they could just commit to the next level of classes.

Representatives urged prospective students to charge the fees to their credit cards if they needed to, according to court documents — and promised that a few more thousand dollars would change their lives.

Instead, those students sued, saying Trump and his eponymous university defrauded them. The case has its final pretrial conference in May. When it goes to trial, Trump will almost certainly have to testify.

Trump University implied students would meet Trump himself

Trump University, which launched in 2005, didn't promise a college degree — just to teach students the secrets of successful real estate investing.

The "university" started with a free 90-minute seminar, continued to a three-day seminar that cost $1,495, and charged $35,000 for the "Trump Gold Elite" package, which promised personal mentorship from experienced instructors "handpicked by Trump."

At every seminar, students were told that the most valuable secrets were only available at the next, more expensive level, according to an investigation from New York Attorney General Eric Schneiderman.

They were encouraged to call their credit card companies and ask for a credit line increase. Instructors told them doing so would raise their credit score, which is sometimes true. But the real goal was to make it easier for students to borrow to afford the more expensive programs.

Scheniderman's investigation uncovered other problems. Mentors were supposedly supposedly experienced real estate investors — but some had never worked in real estate. Some mentors had declared bankruptcy in the past. And some simply disappeared after the three-day seminar, even though students had paid thousands of dollars for a full year of instruction.

Although the promotional materials suggested Trump himself was heavily involved, even in "handpicking" the instructors, there's no evidence that he was.

"He's the most celebrated entrepreneur on earth," one pitch began, according to Schneiderman's lawsuit. "He's earned more in a day than most people do in a lifetime. He's living a life many men and women only dream about. And now he's ready to share — with Americans like you — the Trump process for investing in today's once-in-a-lifetime real estate market. … You'll learn from Donald Trump's handpicked instructor a systematic method for investing in real estate that anyone can use effectively."

Instead, most of the curriculum came from an unnamed "third-party company that creates and develops materials for an array of motivational speakers and seminar and timeshare rental companies."

Students didn't meet Trump. All they got was a consolation prize: the opportunity to take a photo with a life-size cardboard cutout of him.

All this led, unsurprisingly, to some lawsuits

The New York State Education Department warned Trump University in 2005 that it couldn't operate in New York without being a licensed educational institution, a warning it disregarded. The attorney general of Texas opened an inquiry into Trump in 2010.

The New York attorney general's office sued Trump over the university in 2013. A New York court of appeals ruled the case could go forward, with most of its charges intact, in February 2016.

Trump, meanwhile, sued Schneiderman for $100 million, alleging that the attorney general offered to back off the investigation if Trump's family would contribute to his campaign. The university claims that it had a 98 percent satisfaction rate.

And former students have sued Trump in class-action lawsuits. Although Trump "promised 'Trump University,' he delivered neither Donald Trump nor a University," alleges a lawsuit from Art Cohen, a resident of California who paid $36,940 for Trump's classes.

That lawsuit is still pending, as is another class-action suit from former students. And Trump is on the witness list. That means he's likely to have to testify under oath in federal court about his involvement with Trump University in the weeks or months before the Republican National Convention officially chooses the party's nominee.

Believing that a series of seminars or even a year-long mentorship program is anything like an actual university might seem incredibly naive. Calling Trump University a shady for-profit college doesn't go nearly far enough; even the most dubious for-profit colleges provide something akin to an actual degree program.

But Trump's seminars tapped into the same emotions colleges everywhere do — the promise of life-changing learning and success. The problem is that by students' accounts, Trump didn't deliver.