lol.....you are so fucking confused........who gave them copies of Fred Trump's tax returns?........who gave them copies of his trust fund's invoices?......
you were already told. It was started with his sister's financial disclosures as a judge. The reporters looked up the company she reported and it built from there. They discovered Fred was cheating the government and funneling the stolen money to his kids. then they tracked down the people and companies involved in his fraud.
None of this would be necessry if Trump provuided hiis taxes like every other person running has done for 50 years. Now we know why he didn't. He was cheating and still is.