Damien didn't leave Frederick's side the whole night. He briefed Amelia about the discovery, and William joined them in the office some time at dawn. Damien didn't want to take any chances. If he let Frederick out of his sight, Deborah could slip away again, and it might be impossible to catch her if that happened.
They tried to ask Frederick questions about the mission of the assassination of Katherine's parents, but Frederick seemed very stingy with his answers. Damien could tell that the older man was holding back information even though they had already found out about Deborah. Frederick insisted that the details weren't important; it was nothing but a business transaction. She paid, he executed. It was as simple as that.
