From reporters' live tweets at the trial:
A toilet and door were brought into court for demonstration. The police never had the door examined to determine whether marks on it could be from Oscar's prosthesis kicking in the door as he claims. At first the investigator testified there was no evidence that he kicked the door except for his version of events, then admitted it was possible. Police had the prosthetic legs and the door, yet it never asked a toolmarks examiner to do any tests to determine if the door could have been kicked down with a prosthetic leg. .
If the marks on the door did come from the prosthetic leg, it backs up Oscar's claim he was wearing them when he used the cricket bat. The defense said it had tests conducted on the blade from the prosthesis, the door and Oscar's sock (some of which was embedded in the door)and they all match. Also, Oscar's lawyer said their tests show there is varnish from the door on the prosthesis.
There were pieces of wood from the door right there on Feb. 14 but the investigator (who didn't take over the case until March) says he didn't see them. "This is the first time I've seen these pictures. This is the first time I've seen these splinters, these pieces of wood."
Also, photos taken at the scene on Feb. 14 showed police footprints on the door that since have been removed. Defense lawyer Barry Roux says police walked over the door (i.e. they trampled on the evidence.)
The investigator acknowledged that while the door was in the safekeeping of the forensics unit, it somehow happened to get serious marks on it which did not exist on March 8 when it was taken back to Oscar's house (in a body bag.) He can't explain the marks. He said the door should have been under lock and key with only controlled access. He acknowledged the door was not in the same condition on Feb. 14 and when he got it in March.
A photo Roux presented that was taken at the crime scene on Feb. 14 shows police shoe prints on a panel of the door, near the bullet holes. The bullet holes were below the door handle. Here's the photo of the bullet holes.
Another comment that may come back to bite the investigator: He was asked why, when first learning of Oscar's version of events, which he said was last week, he didn't ask for tests to be done on the door. He said by that time he had already closed his investigation and "I'm not going to bother with his version."
Tweet from BBC reporter Andrew Harding at the end of the day:
Day 8 ends and I'd say the prosecution still hasn't convincingly shown that ##OscarPistorius version of events that night MUST be false.