Republican Wisconsin Sen. Ron Johnson sent a letter Wednesday to the Federal Bureau of Investigations (FBI) and the Department of Justice (DOJ) calling for information related to the raid of former President Donald Trump’s Mar-a-Lago residence.

Johnson said any FBI or DOJ employee who has witnessed wrongdoing should reach out to his office immediately.

In the letter, first obtained by the Daily Caller, Johnson called the raid “deeply concerning” and “unprecedented.” Johnson also said he understands that other members of Congress have requested the two agencies provide a full explanation for the raid at Mar-a-Lago and that he is also requesting that information.

However, Johnson added that due to the FBI and DOJ’s “history of lack of transparency and obstruction” of his investigations, he is not confident that their explanation for the raid will be honest.

Johnson then called for the “brave men and women” who work at the FBI and the DOJ and are “frustrated and concerned” with what is going on at their agencies to “come forward” and share their concerns with his office.