In the summer of 1980, Donald Trump faced a big problem. For six months, undocumented Polish laborers had been clearing the future site of Trump Tower, his signature real estate project on Manhattan’s Fifth Avenue, where he now lives, maintains his private offices and hosts his presidential campaign.

The men were putting in 12-hour shifts with inadequate safety equipment at subpar wages that their contractor paid sporadically, if at all. A lawyer for many of the Poles demanded that the workers be paid or else he would serve Trump with a lien on the property. One Polish worker even went to Trump’s office to ask him for money in person, according to sworn testimony and a deposition filed under oath in a court case.

For help, Trump turned to Daniel Sullivan, a 6-ft. 5-in., 285-lb. labor consultant, FBI informant and future officer of the Teamsters Union. “Donald told me he had difficulties …,” Sullivan later testified in the case. “That he had some illegal Polish employees on the job.”

Sullivan had been helping Trump negotiate a casino deal in New Jersey at the time, and he testified that he was shocked by Trump’s admission. “I think you are nuts,” Sullivan testified that he told Trump. “You are here negotiating a lease in Atlantic City for a casino license and you are telling me you have got illegal employees on the job.”

For 36 years, Trump has denied knowingly using undocumented workers to demolish the building that would be replaced with Trump Tower in 1980. After Senator Marco Rubio raised the issue of undocumented Polish workers during a Republican primary debate this year, Trump described himself as removed from the problem. “I hire a contractor. The contractor then hires the subcontractor,” he said. “They have people. I don’t know. I don’t remember, that was so many years ago, 35 years ago.”

But thousands of pages of documents from the case, including reams of testimony and sworn depositions reviewed by TIME, tell a different story. Kept for more than a decade in 13 boxes in a federal judiciary storage unit in Missouri, the documents contain testimony that Trump sought out the Polish workers when he saw them on another job, instigated the creation of the company that paid them and negotiated the hours they would work. The papers contain testimony that Trump repeatedly toured the site where the men were working, directly addressed them about pay problems and even promised to pay them himself, which he eventually did.

The documents show that after things got ugly over unpaid wages, Trump sought Sullivan’s advice on the workers and their immigration status. At one point, a lawyer for the Poles testified, Trump threatened, through his own lawyer, to call the Immigration and Naturalization Service and have the workers deported. And when the Labor Department launched a probe of the Polish laborers, Trump again called Sullivan for help, asking him to meet the federal investigator at Trump’s office, according to the documents.

Testifying at a 1990 trial where he faced a charge of participation in a breach of fiduciary duty, Trump told a federal judge he “still didn’t know” if the workers were undocumented, arguing that he had hired a subcontractor who employed them and that he personally “wasn’t very involved in that whole process.” His lawyers also questioned the credibility of Sullivan, who had been convicted of tax evasion in a separate case. When contacted Aug. 23 by TIME for comment on the documents, Trump replied with an emailed statement. “The laws were totally different thirty five years ago,” he wrote in the message. “The building, Trump Tower, turned out to be one of the most successful and iconic buildings ever built. Do you have nothing better to write about than a story that is 35 years old and filled with half truths and false information?”

Later that day, as part of a political pivot designed to soften his image with minority and centrist voters, Trump told an interviewer he might reconsider the hard-line stance against undocumented immigrants that has been a centerpiece of his campaign. Since shortly after launching his bid for the presidency, he has promised to rid the nation of its 11 million undocumented workers, possibly by employing a “deportation force,” and to suspend issuing new green cards in order to force employers to hire from the citizen labor pool. He has regularly described undocumented workers as an economic threat to U.S. citizens. “They’re taking our manufacturing jobs,” he said at a rally in Phoenix in July 2015. “They’re taking our money. They’re killing us.”

Thirty-six years ago, at the beginning of his career, he saw things differently.

Trump Tower has never been just another building project for Donald Trump. And in 1980, it was something of a personal obsession. He had started in real estate in Queens, working for his father, who had prospered in the outer boroughs. In 1979 he managed, through charm, persistence and hard work, to secure the lease on the old Bonwit Teller building at 56th Street and Fifth Avenue, eventually signing a 50-50 deal with the property owner to develop what would be the city’s tallest glass structure on the site. Facing zoning restrictions, Trump made large donations to politicians and curried favor with powerful members of the New York board of estimate, which approved a zoning variance for the project.

With the approvals in hand, Trump set about preparing to build. One day in late 1979, he was inspecting renovation work being undertaken by a tenant in a building he owned next door to the site, and saw the Poles at work, according to testimony given to the court by the foreman overseeing the job. The foreman testified that Trump personally approached him to ask who they were. “Those Polish guys are good, hard workers,” court documents say the foreman recalled Trump saying. Soon afterward, Trump met with the workers’ boss, a man named William Kaszycki, at Trump’s lavish office across Fifth Avenue, Kaszycki later testified.

Kaszycki’s company specialized in window and job-site cleaning and had never done the heavy demolition work required to remove a 12-story building in midtown Manhattan. Kaszycki testified that Trump told him to start a new company to do the demolition work and directed him to get new and different insurance for the job. Kaszycki, who has since died, testified that he accepted Trump’s $775,000 fee offer flat out. And with Trump offering an additional $25,000 if the building came down quickly, Kaszycki promised him that the Poles would work day and night, seven days a week.

And they did. From January to March 1980, they sneaked over from the job next door and worked two shifts, one from 6 a.m. to 6 p.m., the other from 6 p.m. to 6 a.m. Some later testified that they worked 24-hour shifts. They were paid $4 to $5 an hour, court documents show, which at the time was less than half the prevailing union wage and just above the state minimum wage of $3.10 an hour. Tearing down walls, cutting pipes and pulling electrical wires is dangerous work, and unlike union workers who later joined the job, most of the Polish workers lacked safety equipment like hard hats, according to the testimony of several former workers. A large piece of steel fell on the arm of one worker, Albin Lipinski, breaking several bones and permanently disfiguring his fingers.

But it was a dispute about money, not safety and long hours, that would later cause Trump so much trouble. Five miles east of the Fifth Avenue job site, at a two-story tin-sided house in the heavily Polish neighborhood of Maspeth, Queens, a middle-aged lawyer named John Szabo started getting visits in March 1980 from undocumented Polish laborers who said they were not being paid for their work. Before long, he would have dozens of clients from the same job. Szabo contacted Kaszycki, who was spending much of his time in Florida, but couldn’t reach him. So in late March, Szabo called Thomas Macari, a vice president in Trump’s operation, according to Szabo’s testimony. Macari, who could not be reached for comment, was overseeing the demolition job on a daily basis, according to the testimony of the Poles, Kaszycki and others in the case. If his clients weren’t paid, Szabo said, he would serve Trump with a mechanic’s lien, a powerful legal device that gives a laborer partial claim to the title of a property on which he has worked.

Soon Trump, who toured the site on multiple occasions, according to the testimony of witnesses, had to address the issue himself. One evening in the spring of 1980, he met with some of the workers at the Bonwit Teller building, according to the testimony of one of the Poles on the job, Joseph Dabrowski. Kaszycki hadn’t been showing up on the job, and the Poles were angry about not being paid. Trump told them that if Kaszycki left the job for good, he would pay them himself, Dabrowski testified. And initially he made good on that promise. Trump used a bank account that required his signature to pay Kaszycki’s creditors, and Macari opened a new account requiring his own signature to pay the demolition workers. Macari paid the Polish workers cash for Trump, according to the sworn testimony of multiple witnesses.

But still the Polish workers were paid inconsistently. Lipinski, who had become a foreman after his arm was crushed by the steel beam, took matters into his own hands. Around noon one afternoon, he walked across Fifth Avenue and into Trump’s office, Lipinski testified. “He spoke to the secretary and was surprised the secretary let him speak to Trump,” Lipinski’s son Jozef says in an interview this summer, sitting next to his father in his apartment in New York. Jozef says his father told him and his brother the story throughout their childhood: “Trump told him, ‘I paid the checks and anything I owed to the other guy, and he’s supposed to pay you.'”

Now 80, Albin Lipinski is a U.S. citizen. Speaking through an interpreter at his home, he displayed his hand, still scarred from the accident, but says he supports Trump for President. Twenty-seven years after signing an affidavit about his meeting with Trump and testifying under oath about it, he now says he did go to Trump’s office but never met Trump. “I went to the office because I was mad I wasn’t being paid,” he says through a translator, but “I never met Trump.” Jozef and his brother say their father has begun forgetting things in his old age.

By early June 1980, the Polish workers’ unpaid wages totaled over $100,000. It was at this point, Sullivan later testified, that Trump asked the labor consultant for advice about the laborers. “I told him to fire them promptly if he had any brains,” Sullivan testified. Sullivan died in 1993.

Trump initially ignored the advice. On June 27, 1980, the Poles’ lawyer, Szabo, went to Trump’s office and served Trump with a mechanic’s lien, Szabo testified. Worse, the Polish workers were threatening violence, according to Sullivan’s testimony. “Donald called me at my home in Pennsylvania on June 27th, 1980, and asked could he see me immediately,” Sullivan testified. “He needed some help because the employees on the Bonwit Teller were threatening to hang a fellow named Tom Macari off the building and would I come to New York as soon as possible.”

At his office on Fifth Avenue the next day, Trump told Sullivan he was in a bind: if he didn’t have the Bonwit building down by Sept. 1, he said, he was going to have to pay real estate taxes on it, Sullivan testified. Sullivan persuaded Trump to fire the Poles and rely only on union workers to get the building down.

Worried the Poles would never get paid, Szabo put a second and third lien on the property. On Aug. 8, he called Macari and told him that because Trump had been paying the Poles, he was legally their employer. That meant that under the Fair Labor Standards Act, Trump couldn’t sell any space in the tower until Szabo’s clients were paid.

Forty-five minutes later, Szabo testified, he received a call from a man who identified himself as a Mr. Barron from Trump’s legal department, who said Trump was going to sue Szabo for $100 million for wrongful filing of mechanic’s liens. At trial, Trump admitted that both he and a senior executive at the company had used the name Barron as a pseudonym. “I believe I occasionally used that name,” said Trump. But in this case, Macari said under oath that it had been he who called Szabo while posing as Barron; Szabo testified he didn’t recognize “Barron’s” voice.

Szabo wrote a long letter defending his actions and laying out his case under the law and sent it to “Barron” on Aug. 18. A few days later, Szabo testified, he received a call from a real lawyer for Trump, Irwin Durben, who said Trump was threatening to ask the Immigration and Naturalization Service to have the Poles deported.

By the fall, the Labor Department was investigating Trump and Kaszycki’s use of the undocumented workers. That winter, a Labor Department official made an appointment to inspect Trump’s employment records at the office across from the work site. Trump called Sullivan and asked him to attend the meeting with the federal investigator, according to Sullivan’s testimony. In the end, Szabo and the Labor Department won a judgment of $254,523.59 against Kaszycki. Trump never had to pay the Poles another cent.

None of this history would have been preserved at the federal court storage facility near Kansas City, Mo., but for a separate fight over money and Trump’s use of the Polish workers. According to the contract Kaszycki had signed with Local 95 of the House Wreckers Union, he and Trump were supposed to pay into the union’s pension and welfare fund a percentage of every man-hour worked on the project, whether it was done by union or nonunion workers.

A dissident member of Local 95, a former boxer named Harry Diduck, who has since died, realized Trump and Kaszycki had been paying the pension fund only for the hours the few dozen union workers had put in, not for the hours the Poles had worked. In 1983, Diduck and his lawyers, Burton Hall and Wendy Sloan, sued Kaszycki, the union president and subsequently Trump and others for the $600,000 they claimed Trump and his partners owed the pension fund.

Over time, Sloan amassed thousands of pages of testimony from the Polish workers, Sullivan, Szabo, Macari and dozens of others. Trump fought her at every step. When she tried to depose him, he stormed out after two hours complaining that he was being harassed, necessitating a court order forcing another deposition. The case ran for 15 years. The initial judge in the matter found that Trump had participated in defrauding the union pension fund. It then went through an appeal and multiple battles back at the district court under three different judges. Finally, in 1998, when the question of whether Trump was the legal employer of the Poles was set to go to a jury trial, Trump settled. No one knows how much he ended up paying to compensate the union pension fund. The deal remains sealed by the court. TIME and the Reporters Committee for Freedom of the Press have asked the court to make the deal public.

But the other records in the case have been sitting in storage ever since. They include a ruling by the U.S. Court of Appeals for the Second Circuit in New York City that gave both sides partial victories. It began with a swipe at the union president and the later complicity of Trump’s organization: “This case illustrates an immutable law with respect to falsehoods–as immutable as the one respecting gravity Sir Isaac Newton conceived upon seeing an apple fall from a tree: having first manufactured a falsehood, a person is forced to invent more to maintain it; yet, as here, in the end, time generally reveals what a falsehood hopes to hide.”

Sullivan put it more bluntly in 1990 to People magazine. “It was disgusting how he used people,” Sullivan said. “I said, ‘Don’t exploit them like that. Don’t try to f-ck these poor souls over.’ It baffled me then, and it makes me sick even now that he knowingly had these Poles there for the purpose of Trump Tower at starvation wages. He couldn’t give a sh-t because he’s Donald Trump and everybody is here to serve him. Over time he became more and more monstrous and arrogant. I asked myself, ‘How long is it going to take for all of this to catch up with him?'”

–With reporting by MERRILL FABRY and CELINE WOJTALA/NEW YORK and MELISSA AUGUST/WASHINGTON

This appears in the September 05, 2016 issue of TIME.

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