Pistorius has argued in court that he was closing his balcony doors when he heard a noise from the bathroom. Fearing an intruder, and without his prosthetic legs on, he grabbed a gun from under his bed and fired through the closed bathroom door, he told the court.
But prosecutors say that's implausible, that the gun's holster was found under the side of the bed where Steenkamp slept, and that Pistorius would have seen she wasn't there. Prosecutors also say the angle at which the shots were fired shows Pistorius was already wearing his prosthetics when he fired.
Pistorius' family and running coach continue to stand by him.
In a statement released today, Pistorius' coach Ampie Louw said he was shocked by the developments, but still looking forward to getting Pistorius "back on the track."
"I am still in shock following the heart-breaking events that occurred last week and my thoughts and prayers are with both of the families involved," Louw said. "I had spent some time with Reeva recently after being introduced to her by Oscar, giving her training tips and advice and she would often be at the track with me whilst Oscar was training."
Louw said he found Steenkamp "delightful" and "friendly," like Pistorius, and said he thought the two were happy together. He has been Pistorius' coach for nine years.
"In my 35 years of coaching, never have I worked with an athlete who has such an incredible work ethic and treats every training session very seriously and has the focus, the commitment and the talent that every coach dreams of," he said. "I pray that we can all, in time, come through this challenging situation following the accident and I am looking forward to the day I can get my boy back on the track."
Pistorius' family said they "fully respect" the bail hearing process and are patiently waiting for Friday's decision.
"We are strong and supportive as a family, for Oscar, but we understand that this is in the best interest for all," his uncle Arnold Pistorius said in a statement today.
"This is a unique, emotional and difficult time for us all," he said. "Our hearts and thoughts are with the family of Reeva Steenkamp during their time of bereavement".
Meanwhile, Steenkamp's cousin told CNN that she wants to believe Pistorius' story.
"That is what in my heart, I hope and wish is the truth, because I would not like to think my cousin suffered," Kim Martin, Steenkamp's cousin, told CNN's Piers Morgan. "I would not like to think that she was scared."
Pistorius has been dropped by at least two of his sponsors, Nike and Thierry Mugler.
ABC News' Sifiso Khanyile contributed to this report.