PRETORIA, South Africa (AP) — Blood on the stairs, walls and furniture, a cocked 9 mm pistol, bloody towels, fallen wall tiles. Like pieces of an unfinished puzzle, the photos of the blood-splattered interior of Oscar Pistorius’ home gave a fragmented picture Thursday of his girlfriend’s violent end.

One of the first police officers to arrive at the scene testified at the athlete’s murder trial that he followed a “trail of blood” when he got there.

Recounting what he saw in macabre detail, former police colonel G.S. van Rensburg said he traced spots and bigger blood marks downstairs where Reeva Steenkamp lay dead from three gunshot wounds, then followed them across the floor, up the stairs, through a small lounge area and into Pistorius’ bedroom.

Ultimately, he reached the bathroom where the double-amputee Olympian shot his girlfriend in the early hours of Valentine’s Day last year.

There, van Rensburg said he found Pistorius’ gun, its hammer back and safety off, lying on a mat. Nearby were spent bullet casings, cellphones and a blood-soaked towel, as well as the cricket bat Pistorius says he used to smash open the toilet door to get to the fatally wounded Steenkamp.

In the toilet cubicle, a dark pool of blood was on the floor as well as wooden splinters from the broken door.

The mat the gun lay on was clean, in glaring contrast to the blood stains all around it, head prosecutor Gerrie Nel noted.

The 27-year-old Pistorius faces 25 years to life in prison if convicted of murder, and also faces three firearms charges. He has pleaded not guilty and says he shot the 29-year-old model by mistake, believing she was an intruder hiding in the toilet cubicle.

Prosecutors charge he intentionally shot Steenkamp after an argument.

Using the photos, the prosecution created a detailed picture of the scene. One showed a gun holster on the side of the bed where Pistorius says Steenkamp was sleeping that night. The size of the bedroom suggested Pistorius would have had to walk close to where he says he thought she was still sleeping to get to the bathroom.

Pistorius mostly kept his head down, avoiding the TV monitors where the images were shown. The screen next to Pistorius was switched off before the exhibit began.