Two days after Donald J. Trump left the White House, The New York Times published a story about how one of his last acts as president had been to commute the 10-year sentence of Jonathan Braun, a marijuana smuggler who had ongoing legal problems and a reputation for making violent threats.

In his final weeks in office, Mr. Trump had used his pardon power on behalf of a parade of loyalists, as well as scores of others who were not big political names. But few of them stood out like Mr. Braun, who was still under investigation by the Justice Department in an entirely different matter: for gouging small businesses through high-interest loans.

At the time of the commutation, the New York State attorney general and the Federal Trade Commission were also after Mr. Braun for making predatory loans. Among other things, they accused him of threatening borrowers who owed him money. And his family had told others they were willing to spend millions of dollars to get him out of the prison sentence he had just started to serve on the drug charges.

With Mr. Trump running again for president and suggesting that he again intends to make full use of his pardon powers if elected, The Times decided to take a closer look at how the pardon came about and what it said about the Trump White House’s standards for clemency.

Here are the main takeaways from our investigation, which is based on documents and interviews with current and former officials and others familiar with Mr. Braun’s case:

Mr. Trump’s decision to commute Mr. Braun’s sentence undermined what had been an ambitious Justice Department investigation being led by the U.S. attorney’s office in Manhattan into predatory lenders in the merchant cash advance industry by pulling the rug out from under investigators who had been in negotiations with Mr. Braun about cooperating with them.

Prosecutors felt they needed an industry insider to flip on others in the business, explain the intricacies of lending agreements and serve as a narrator on the witness stand. In Mr. Braun, who had made clear he was desperate to get out of prison, they thought they had an ideal candidate. They were still going back and forth with his lawyer about a deal that would have freed him from prison when Mr. Trump commuted his sentence.