When your lawyers need lawyers, it’s usually a bad sign. When your lawyers have their offices and homes raided, it’s a really bad sign. News that federal investigators on Monday took the extraordinary step of executing a search warrant at the legal office of Michael Cohen, President Trump’s longtime personal attorney, indicates that Cohen is suddenly in serious legal jeopardy of his own. And although the investigation is not directly related to the Mueller probe, it’s yet another example of the legal walls closing in on one of the people closest to Trump — someone who may have a wealth of information about the president’s own conduct.

The FBI executed the search warrants at Cohen’s New York office and his home and hotel room. The warrants were obtained by federal prosecutors in the Southern District of New York. According to a statement from Cohen’s attorney, prosecutors informed him their investigation is, “in part,” based on a referral from special counsel Robert S. Mueller III.

The first thing to note about this striking development is that the warrant was not obtained by Mueller himself. Whatever the subject matter of this particular investigation, it apparently falls outside of Mueller’s jurisdiction and thus resulted in his referral to the New York prosecutors. So we know the potential crimes that led to the search today do not directly relate to Mueller’s inquiry into any conspiracy with Russians to influence the election or related crimes such as obstruction of the special counsel’s investigation.

We also know that a search warrant, unlike a grand jury subpoena, requires prosecutors to go before a federal judge to demonstrate probable cause that a crime has been committed and evidence of that crime can be found in the premises to be searched. Before approving a search of a lawyer’s office, a judge would want to be satisfied that there was some substance behind the prosecutors’ allegations. This is not just some prosecutorial fishing expedition; it bears the imprimatur of a federal judge.

We don’t know for certain the nature of the Southern District’s investigation. The potential crime outside of Mueller’s jurisdiction to which Cohen has been linked most directly relates to the $130,000 payoff to porn star Stormy Daniels just days before the presidential election. If Cohen made that payment himself or facilitated the payment from another individual or company, it could be deemed an illegal contribution to Trump’s campaign. There could be other alleged offenses, such as tax or bank fraud violations, surrounding any such payments as well. Or there could be other non-Stormy-Daniels-related allegations about Cohen’s conduct that have not yet surfaced publicly.

This was not just any search warrant; that the raid took place at a lawyer’s office further highlights the seriousness of the investigation. Searches of an attorney’s office are extremely rare and are not favored, due to their potential to impinge on the attorney-client relationship. Prosecutors must jump through multiple hoops to get such a warrant approved, both within their own office and at the criminal division of Main Justice. (Notably, this would likely have included approval by Trump’s own guy, the new interim U.S. attorney for the Southern District, Geoffrey S. Berman, who was just appointed by Attorney General Jeff Sessions this past January.)

Prosecutors are also required to consider less intrusive alternatives to a search warrant, such as a subpoena, if practical. Approval of a search warrant suggests prosecutors were able to demonstrate not only the gravity of the potential case but also the risk that evidence might be destroyed or otherwise go missing if they pursued a less aggressive option.

Cohen, and perhaps the president, will likely argue that this raid violates the attorney-client privilege. Indeed, on Monday evening, Trump said it was “a disgrace what’s going on.” In a search like this, prosecutors typically set up a privilege team or “taint team” of investigators not involved in the case to review potentially privileged documents and shield those from the team actually involved in the prosecution. There is an exception to the attorney-client privilege if communications to an attorney are used in furtherance of a crime or fraud; that could come into play here as well. And documents related to anything Cohen did on his own — after all, Trump has denied knowing about the payment to Daniels — are likely not privileged if they do not contain attorney-client communications. Documents are not automatically privileged simply because they passed through an attorney’s hands.

There may well be litigation concerning whether particular records seized during this search are protected by privilege. But seizing the records now allows prosecutors to ensure that the integrity of the evidence is maintained while those legal issues are sorted out.

Cohen, someone extremely close to Trump and who has been known as the president’s “fixer,” appears to have serious legal problems. If federal prosecutors feel they have enough on you to execute a search warrant, it’s never a good sign — just ask Paul Manafort. And to the extent that Cohen, part of Trump’s innermost circle, might have knowledge relevant to Mueller’s inquiry, we can’t rule out the possibility that his own legal troubles could induce him to cooperate in the Russia investigation.

Hold on tight — it’s only Monday.