The FBI’s execution of a search warrant Monday at former President Donald Trump’s Mar-a-Lago estate in Florida has prompted questions about the methods federal law enforcement officials use in their investigations.

Here are answers.

How does a federal search warrant work?

The Fourth Amendment of the U.S. Constitution protects against unreasonable searches and seizures. However, federal law enforcement officials may seek search warrants if they believe criminal evidence they seek could be moved, concealed, altered or destroyed if they used less intrusive measures to obtain it. 

First, they must swear, under oath, to a series of facts in an affidavit to a federal magistrate judge or district court judge in the area where the warrant is to be executed. The application must show “probable cause” that a crime has been committed and that evidence of the crime is likely to be found at the location to be searched.

In this case, the warrant could have been approved by a judge in Washington, D.C., because the FBI investigation is believed to focus on classified White House documents, said Columbia Law School professor John Coffee.

Search warrant applications limit the search to the specific evidence being sought – a safeguard aimed at preventing investigators from conducting overly broad searches.

Search warrants are not an indication someone is guilty.

FBI agents seeking search warrants involving high-level officials often will consult with federal prosecutors before proceeding.

“For someone like the former president, it is highly likely that investigators would review a search warrant application at the highest levels of the Department of Justice,” said Stephen Saltzburg, a law professor at George Washington University and a former U.S. deputy assistant attorney general.

Search warrants are secret until federal investigators execute them. And they can’t be challenged by the person whose home, business or other location is searched.

“It can be a complete surprise,” Saltzburg said. “It usually is.”

After the warrant has been executed, investigators must file a document with the court that lists each piece of evidence that was seized. They must also leave an inventory of the seizures at the location where the search was conducted.

Search warrants may be challenged in court afterward if there is evidence investigators failed to meet the probable-cause requirement or otherwise misled the judge who approved the warrant.

In a federal indictment unsealed earlier this month, federal prosecutors charged members of the Louisville Metro Police Department with falsifying the affidavit they filed to obtain a search warrant for the home of Breonna Taylor, who was shot and killed by officers who executed the warrant.