Federal agents reportedly raided the Chicago City Hall office of a lawyer who had previously done tax work for US President Donald Trump.

Federal agents showed up unannounced at the City Hall office of Finance Committee Chairman Ed Burke, covered the windows and floors with brown paper and ordered everyone to get out, the Chicago Sun-Times reported on Thursday.

About 15 agents arrived at City Hall early Thursday morning, bringing their own boxes. Some then went across the street to the underground parking garage at the Daley Center to find Burke’s car, but it wasn’t there, the reports said.

The agents spent approximately half a day inside Burke’s office, leaving with the box of files, a computer and two computer monitors.

A spokesman for the US attorney’s office declined to comment on the event when contacted by the Sun-Times. Burke issued a statement Thursday afternoon regarding the raid.

“As you are aware, there have previously been several other investigations such as this. In every instance, we cooperated fully. And in every instance nothing has been found,” Burke said, according to Chicago Sun-Times. “So once again we will be cooperating fully and I am completely confident that at the end of the day nothing will be found amiss in this instance either.”

Burke’s law firm of Klafter & Burke has worked with Trump’s companies repeatedly to reduce the property tax load on Trump Tower and his other properties in Chicago, according to the Sun-Times. Over his 12 years working for Trump, Burke was allegedly able to cut the property taxes on the downtown tower by more than $14 million, the newspaper said.

Burke quit working for Trump this summer, citing “irreconcilable differences” in letters filed with the Illinois State Property Tax Appeal Board.

The raid took place as Trump’s former personal attorney, Michael Cohen, entered into a plea agreement to cooperate with special counsel Robert Mueller’s investigation into alleged Russian interference in the 2016 election and collusion with Trump’s team.

Trump has repeatedly denied all allegations, submitting written answers to a list of questions from Mueller last week. Moscow has also consistently denied all such allegations.