FBI Director Christopher Wray revealed during a marathon testimony on Wednesday that investigators still do not know if former President Donald Trump was grazed by a bullet or a piece of shrapnel during his attempted assassination.

Twice during the hours-long session, Wray told lawmakers that the FBI was still working to determine what exactly struck the former president on his right ear during a rally in Butler, Pennsylvania. “My understanding is that either it [a bullet] or some shrapnel is what grazed his ear,” Wray told Rep. Kevin Kiley (R-CA).