According to reports, investigators were concerned about Trump storing sensitive documents at Mar-a-Lago.
The FBI's decision to raid Trump's property was preceded by these fears.
It is not clear what documents Trump kept, but he would have had access to highly classified material.
According to The New York Times, federal officials felt they had no other choice but to raid Mar-a-Lago to get the classified documents back.
The private residence of a former president was raided by the FBI because they were worried that the highly sensitive documents were still at Mar-a-Lago. Two people briefed on the classified documents talked to the paper about the sensitive nature of the documents.
The FBI subpoenaed Trump for documents before the raid, according to the Times report.
Trump and his staff were required to give their records to the National Archives before they left office. The archives said that Trump took classified material to Florida. The archives tried for months to get more documents from Trump and his attorneys.
Clinton's use of a private email server to conduct official business was a point of contention for Trump and his supporters. The level of classification of the material at Mar-a-Lago is not known. The president has the power to declassify anything at will.
When Trump was in office, it was reported that he discussed codeword level classified material with the Russian foreign minister and ambassador. Codeword is one of the highest levels of classification and is used to limit the number of people who know sensitive information.
Multiple Trump White House officials disagreed with The Washington Post's report about Trump's alleged disclosure of codeword-level information.
Business Insider has an article on it.