Spencer Platt/Getty Donald Trump
Shuttered for the summer season, the sprawling property's white front gate was closed, and the employee entrance, usually left open, was blocked off by a security guard in a golf cart and a herd of parked vehicles that included black SUVs with tinted windows and police cars.
Across the street, on the Southern Boulevard bridge that connects Palm Beach to West Palm Beach, about 60 Trump followers were gathered, waving American flags and holding signs and banners that read, "Thank you Trump," "Democrats are Fascists," "Trump Won" and other supportive messages in close proximity to reporters and TV crews.
The former president has been away all summer; he was last seen at Mar-a-Lago before Memorial Day Weekend. While the FBI conducted its search of the property, which reportedly focused on Trump's office and personal quarters, the former president was in New York inside Trump Tower. There on Fifth Avenue, the energy was reportedly less calm.
"Donald is furious yet scared," a source close to Trump tells PEOPLE. "He feels victimized and is calling everyone he trusts to give him advice and reassure him that this is a witch hunt. He is buoyed by the Republican support [after the] invasion of privacy."
The FBI searched the property as part of an ongoing investigation into an alleged mishandling of White House records, including potentially classified materials, Politico, CNN, The Washington Post and other news outlets reported.
It's one of two known investigations underway by the Justice Department, which is also looking at the former president's role in the Jan. 6, 2021, attack on the U.S. Capitol and alleged efforts by Trump and his supporters to overturn the results of the 2020 presidential election that Biden won.
Monday's development, which the source said frightened Trump, could affect his political calculations as he weighs a third run for the presidency in 2024.
GIORGIO VIERA/AFP via Getty A law enforcement officer stands outside Trump's Mar-a-Lago residence
Trump has repeatedly hinted at plans to launch a campaign and has even said all that's left to decide is when to announce.
But the source suggests that could all be an act, telling PEOPLE that though Trump will act like he's running, talk like he's running and raise money like he's running, he may not actually vie for the seat.
"He has a good life now and is enjoying it," the source says.
"He is definitely making the moves to run but, in the end, I don't think he will unless he is convinced criminal charges are coming," adds the source.
As an active candidate for the presidency, Trump could further push the argument that the criminal investigations he's facing are politically motivated.
As a sitting president, he could be even more protected from prosecution given the Justice Department's long-standing practice of never charging a sitting president with a crime. He would also again be able to appoint and remove officials from the DOJ and FBI.
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"If he wasn't running before, he is now," a person close to the former president told NBC News in the wake of the FBI's Mar-a-Lago search. "It pisses him off that they can do this to him. One way to get it to stop is to control the government again."