I needed to examine as many loans as possible, to see if they were as unusual and reckless — and predatory — as some of my sources said they were. But how?

I got a lead from an unexpected source: the lenders themselves.

After prices had started crashing, the lenders in the industry had tried to squeeze money out of borrowers. Many of them had filed lawsuits against borrowers — lawsuits which had to include copies of the loans.

I ultimately reviewed 500 of these loans, and I saw disturbing patterns: Almost none of them included a large down payment. Almost all of them required the borrower to repay everything within three years, which was impossible. There were a lot of interest-only loans, and a wide variety of fees, including charges for paying loans off too early. Many of the loans required borrowers to sign away their legal rights.

Armed with the loan documents, I started calling dozens of current and former industry bankers, brokers, lawyers and investors. Some pointed me to disclosures that lenders had filed with the government, which were enormously helpful. Others shared internal records, which were even better.

New York City did not have reliable digital data on medallion sales, so I used paper records to build a database of all the 10,888 sales between 1995 and 2018. The city taxi commission had never analyzed the financial records submitted by medallion buyers, so I did. Nobody knew how many medallion owners had gone bankrupt because of the crisis, so I convinced my boss to pay a technology company, Epiq, to create a program that sped through court records and spat out a tentative list — and then two news assistants helped me verify every result.