A forensic geologist on Tuesday testified that it was probably pitch black in the bedroom when Oscar Pistorius shot and killed his girlfriend Reeva Steenkamp.
The 27-year-old athlete is accused of murdering the model at his luxury Pretoria East home on Valentine's Day last year.
He also faces gun-related charges for two separate shooting incidents, one from a moving vehicle and another at a northern Johannesburg restaurant.
The athlete also faces a charge of illegal possession of ammunition.
He pleaded not guilty to all charges on the first day of his murder trial in the North Gauteng High Court on 3 March.
Defence advocate Barry Roux on Tuesday asked forensic expert Roger Dixon about the light in the bedroom and about what the neighbours may have seen.
He said it was a moonless morning on the night Pistorius shot and killed the Port Elizabeth model.
Dixon further confirmed the light bulb in the toilet was not functioning, which contradicted earlier testimony given by a state witness.
"The bulb in the toilet itself was not functional."
He said both the lights to the bathroom and toilet are controlled from outside the room.
Dixon also presented new photographs to the Pretoria court, which he said was a replication of what the conditions may have been like on the morning of the deadly shooting.
Roux confirmed Dixon conducted light tests at the 'Blade Runner's' Silver Woods Country Estate home.
The toilet door also came under scrutiny as Roux attempted to convince the court his client was not guilty of murder.
Dixon took the court through the sounds of a cricket bat hitting the door and the marks made by the bat.
The forensic geologist conducted sound tests at Pistorius's house and played these back to the court.
He said the athlete kicked the toilet door with considerable force to get to Steenkamp, resulting in varnish sticking to the bottom of the athlete's prosthetic leg.
Dixon also took the court through the use of a cricket bat to smash through the toilet door.
White fibres from Pistorius's sock on the prosthetic leg were found on the door.
The state maintains he stepped on the panel once it had already broken off the door and had fallen to the floor.
Dixon also assessed Steenkamp's back wound, saying it was consistent with her falling back on the magazine rack.
Earlier today, the athlete claimed he didn't see the rack in the corner next to the toilet when he found her body, saying it must have moved when she fell.
The state maintains that those wounds were caused by fragments of a bullet.
Earlier on Tuesday, prosecutor Gerrie Nel concluded his cross-examination of the sportsman following five days of intense questioning.
After nine minutes of re-examination, Roux called Dixon to testify.
The matter will resume on Wednesday morning.
Judge Thokozile Masipa is expected to make a ruling on whether the matter will be postponed following a request from Nel.