Federal investigators swept the Penn Biden Center at the University of Pennsylvania following an announcement that the president’s lawyers had discovered classified documents at the offices from his time as vice president, CBS News reports. It is unclear if the mid-November probe discovered any further information or more classified documents. The office building housing the D.C.-based foreign policy research center was used as a periodic office space by President Joe Biden between 2017 and 2019, making use of the location’s sixth floor even before the center formally opened its doors as a new branch of UPenn. So far, authorities have retrieved somewhere between 25 and 30 documents from the space and Biden’s Delaware home. The president says he is fully cooperating with the investigation, and sources who spoke with CBS confirmed that a search warrant was not sought to comb over the property. The documents have since been handed over to the National Archives.