you speak to? >> reporter: pistorius was expressionly as they talked about the missing pieces from the bullet-riddled bathroom door, the door pistorius broke down with a cricket bat to reach his girlfriend after shooting her several times. >> for you to have stated under oath that nowhere that any of those exhibits appeared in sab-13. it can only mean one thing, that it was checked and it could not be found there. >> during the conversations i had, i could not determine where it was. >> reporter: pistorius had told investigators he put on his prosthetic legs before taking down the door. >> i'm in a natural position at the moment with my legs. >> reporter: and on wednesday, the forensic expert tried to undercut his story, testifying that based on the height of the cracks in the door, pistorius was not wearing his prosthetic legs. >> the marks on the door is actually consistent with him not having his legs on. >> reporter: showing photo after photo of the crime scene, the defense revealing that a mark on