In the midst of the duel, Voldemort unsuccessfully tries to possess Harry in an attempt to get Dumbledore to kill the boy, then escapes just as Cornelius Fudge appears, finally faced with first-hand evidence that Voldemort has truly returned.
Voldemort unsuccessfully tries to possess Harry in an attempt to get Dumbledore to kill the boy escapes just as Cornelius Fudge appears, finally faced with first-hand evidence that Voldemort has truly returned. This was in the midst of the duel. This was then.