Attorneys for the financier Jeffrey Epstein had good reason to believe in 2008 that he was safe: After all, he pleaded guilty to solicitation of minors to engage in prostitution in a Florida state court, and while that didn’t stop other states or the federal government from going after him, there was little chance that another legal team would decide to reopen the case. Indeed, the whole point of the 2008 agreement was to permit him to escape a federal indictment.

But on Monday, a new indictment, focused on a criminal conspiracy to traffic in underage girls, came from an unexpected source, the Southern District of New York. And ironically, Mr. Epstein’s prior deal will make it more difficult for him to fight the new charges.

Mr. Epstein can be prosecuted by the Southern District of New York because his agreement was with the United States attorney’s office for the Southern District of Florida. As New York federal prosecutors noted, the agreement does not bind other offices. In fact, Justice Department policy prevents United States attorney’s offices from making agreements that limit other offices.

In most cases, that is not an issue. Prosecutors can bring charges only in jurisdictions where the crime occurred, and typically, if they cut a deal after a long investigation, another office is unlikely to investigate the same crime later.