It was a grueling Tuesday morning when South African double-amputee sprint runner, Oscar Pistorius broke down in tears as he recalled the moment when he shot and killed his model girlfriend, Reeva Steenkamp.

"She wasn't breathing," he sobbed. "I unlocked the door ... And I sat over Reeva and I cried. I don't know how long I was there."

The athlete dubbed "Blade Runner" explained that he believed there had been an intruder inside his home. Pistorius was certain that someone had entered his house by way of the bathroom window and was in his bathroom.  His intention was not to kill or even shoot at Steenkamp, who he claims he was always "besotted" with.

"There's no barrier between me and the bathroom window. I immediately thought that they could be there at any moment. The first thing that ran through my mind was that I needed to arm myself. I needed to protect Reeva and I needed to get my gun," he said.

While grabbing his gun from underneath his bed, Pistorius testified that he whispered to Steenkamp to "get down and call the police."

He then made his way toward the passage from his bedroom to his bathroom. At the time, Pistorius has been on his stumps and did not have his prosthetic legs on.

Before the "moment that everything changed," as described by Pistorius, he heard a noise from behind the door of the bathroom and thought someone was coming out.

In his state of panic, Pistorius decided to take drastic measures. "Before I knew it I fired four shots at the door," he said.  

Soon after he fired his gun, Pistorius went back to the bedroom to find his girlfriend, but she was not there. "At that point, it dawned upon me that it could be Reeva who was in the toilet," he said.

Upon this shocking realization, Pistorius grabbed a cricket bat, broke down the bathroom door, and saw Steenkamp's dead body on the bathroom floor.

"I shouted from the balcony for help, I screamed for somebody to help me. I put my legs on ran as fast as I could into the bathroom. I was just panicked at this point. I didn't know what to make or what to do.

"I was screaming and shouting the whole time. I don't think I've ever screamed liked that. I was crying out for the Lord to help me," Pistorius exclaimed

Pistorius shot and murdered his girlfriend, Reeva Steenkamp In the early morning of Valentine's Day last year.

According to CNN, The judge adjourned the murder trial as Pistorius's emotions unraveled and later ended proceedings for the day.

Pistorius was also a ball of emotions on Monday when he made a tearful apology to Steenkamp's family.

To hear an audio clip of Pistorius's recollection of the gruesome night, click here.