Federal investigators searched Donald Trump’s Mar-a-Lago residence in Florida on Monday bearing a warrant that broadly sought presidential and classified records that the justice department believed the former president unlawfully retained, according to two sources familiar with the matter.

The criminal nature of the search warrant executed by FBI agents, as described by the sources, suggested the investigation surrounding Trump is firmly a criminal probe that comes with potentially far-reaching political and legal ramifications for the former president.

And the extraordinary search, the sources said, came after the justice department grew concerned – as a result of discussions with Trump’s lawyers in recent weeks – that presidential and classified materials were being unlawfully and improperly kept at the Mar-a-Lago resort.

The unprecedented raid of a former president’s home by FBI agents was the culmination of an extended battle between Trump and his open contempt for the Presidential Records Act of 1978 requiring the preservation of official documents, and officials charged with enforcing that law.

For years, Trump has ignored the statute. But the criminal investigation into how he took dozens of boxes of presidential and classified records in apparent violation of that statute when he left the White House last year signals potential legal jeopardy for him for the first time.

The statute governing the wilful and unlawful removal or destruction of presidential records, though rarely enforced, carries significant penalties including: fines, imprisonment and, most notably, disqualification from holding current or future office.

But the justice department may take no further action now that it has secured what sources said were around 10 boxes’ worth of documents in addition to 15 boxes recovered from Mar-a-Lago earlier this year – but what it does next was not immediately clear.

The FBI obtained a warrant for the search, meaning it showed there may be evidence of a crime at the location, which in this case would be the very presence of sensitive government documents that the justice department concluded should be held at the National Archives.

The improper handling of classified materials raised the additional prospect that the FBI might have sufficient basis to open a counterintelligence investigation, amid concerns that the records could have been accessed by individuals not authorized to view secret documents.

On his social media app, Trump on Tuesday denounced the search as a “coordinated attack” that included congressional and federal investigations into his role in the Capitol attack, and state-level probes in Georgia and New York as he weighs running for a second term.

The search warrant appeared to be approved by Florida federal magistrate judge Bruce Reinhart. The attachment to the warrant, describing the “property to be seized”, broadly referred to classified documents and materials responsive to the Presidential Records Act, one of the sources said.

The operation would have likely required approval from the highest echelons of the justice department, former officials and FBI agents said, including attorney general Merrick Garland, and the Trump-appointed FBI director Christipher Wray. An agency spokesperson declined to comment.

One of Trump’s lawyers, Christina Bobb, later said the warrant sought “presidential records”. Trump has not released his copy of the warrant.

In executing the search warrant on Monday, teams of FBI agents wearing nondescript clothes fanned out across the entirety of the Mar-a-Lago resort in Palm Springs, Florida, the sources said. Trump was not there at the time of the raid and learned about it while he was in New York.

The agents searched through storage areas in the basement of the property, the sources said, before moving to Trump’s office on the second floor of the main house, where a safecracking team opened a hotel-style safe, though that contained no records responsive to the warrant.

Later, the FBI agents searched the residence of Trump and his wife, Melania, and navigated through the pocket-door that separates their separate rooms, one of the sources said.

The FBI agents believed the records they were seeking were at Trump’s residence, the sources said, in part through the justice department’s talks with Trump’s lawyers – led by former assistant US attorney Evan Corcoran – about the retrieval of official records from the property.

In early June, the sources said, four justice department officials, including the chief of counterintelligence and export control Jay Bratt, went down to Mar-a-Lago to ask about what materials Trump removed from the White House, and met with Corcoran and Bobb.

The officials asked to see where the White House records were being kept. They were shown the storage facility in the basement where the boxes had been placed, and after looking around for some time, during which Trump dropped by to say hello, the officials left.

Corcoran and Bobb continued to be in touch with the justice department in the weeks afterwards, and complied with a 8 June 2022 letter that asked the basement storage area to be secured with a lock, the sources said.

The justice department is understood, at some point since the investigation was opened in April this year, to have asked for the return of classified materials. Trump’s lawyers are understood to have agreed, and indicated they would go through the boxes to comply with the request.

But that otherwise cordial channel of communication appears to have somehow gone awry – prompting the justice department to take the aggressive step of seeking a search warrant to seize documents – though a person close to Trump disputed this assessment and called it an incomplete account.

The exact inventory of what the FBI removed was still not clear late on Tuesday. Corcoran was in possession of the search return ‘receipt’ but appears to have not divulged its contents even to some associates.

A spokesperson for Trump did not respond to multiple requests for comment. Corcoran declined to comment.