Speaking in a trembling, sometimes hard to hear voice, Oscar Pistorius - the olympic athlete who is accused of murdering his former girlfriend - spoke on the witness stand on Monday for the first time since his trial began.

"There is not a moment an there hasn't been a moment since this tragedy happened that I haven't thought about your family," he told the mother of Reeva Steenkamp. "I wake up in the morning and you're the first people I think of, the first people I pray for."

ALSO SEE: Oscar Pistorius Pleads Not Guilty 

Pistorius is charged of shooting his girlfriend on Valentine's Day last year in his home in Pretoria, South Africa; he says he mistook her for an intruder. 

On the stand, he said the incident still haunts him to this today. 

"I'm scared to sleep. I have terrible nightmares about things that happened that night. I smell the blood and wake up terrified."

ALSO SEE: On Pistorius: How To Build A Sports Hero 

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