A judge in South Africa handed down an acquittal to former Olympic and Paralympic sprinter Oscar Pistorius on the most serious murder charges in the 2013 shooting death of his girlfriend.

Judge Thokozile Masipa could still find Pistorius guilty of lesser charges, such as manslaughter, but said the prosecution did not prove Pistorius acted with premeditation.

Greg Palkot reported from the courthouse in Pretoria this morning, saying the double-amputee track star was quiet and looked confident this morning before the verdict was announced.

Read more from AP and stay tuned to Fox News for word on the rest of the verdict:

Judge Thokozile Masipa said that the prosecution had not proved that Pistorius was guilty of premeditated murder when he shot and killed Reeva Steenkamp in the bathroom of his home on Valentine's Day 2013. If found guilty on that charge, Pistorius could have faced a sentence of life in prison and been required to serve a minimum of 25 years. Pistorius also faces years in jail if found guilty of murder without pre-planning, or of negligent killing. Pistorius could also be acquitted if Masipa believes he made a tragic error.

Masipa told Pistorius he could remain seated on a wooden bench in the South African courtroom until she asked him to stand, and then proceeded to explain her assessment of the testimonies of some of the 37 witnesses who testified at the double-amputee's dramatic trial. This verdict phase was expected to take hours and possibly even two days to fully read out.

Casting doubt on witness accounts of hearing a woman's screams, Masipa said "none of the witnesses had ever heard the accused cry or scream, let alone when he was anxious," apparently acknowledging the possibility that the defense argument that Pistorius had been screaming in a high-pitched voice.

"That in itself poses a challenge," Masipa said of the fact that neighbors had never previously heard Pistorius scream and had no "model" to compare with the screams they heard on the night of Steenkamp's death.

At one point, Masipa said: "I continue to explain why most witnesses got their facts wrong."

Masipa also said she was disregarding telephone text messages between the couple that had been entered as evidence -- prosecutors had submitted text messages that showed tension between them in an attempt to prove that Pistorius had a motive to kill his girlfriend, while the defense submitted messages that indicated mutual affection.

That evidence, the judge said, doesn't prove anything.

"Normal relationships are dynamic and unpredictable most of the time, while human beings are fickle," she said.  

Pistorius has said he mistakenly shot Steenkamp through the closed door of a toilet cubicle, thinking there was an intruder in his home and pleaded not guilty to murder. The prosecution alleges the athlete intentionally killed her after a loud quarrel, which was heard by neighbors.

A key part of the prosecution's case was its assertion that Steenkamp screamed during a late-night alleged fight with Pistorius before he killed her. But Masipa said some of those witnesses who testified to hearing a woman scream that night were "genuinely mistaken in what they heard, as the chronology will show."

That appeared to indicate that the defense had succeeded in raising doubts that Steenkamp ever screamed. The defense says the screaming was instead Pistorius, who was traumatized and desperately calling for help in a high-pitched voice after realizing he had shot Steenkamp in error.

Masipa also cited testimony of an acoustics expert called by the defense, saying it cast "serious doubt" on whether witnesses who were hundreds of yards away in their homes -- as some state witnesses were -- could have differentiated between the screams of a man or a woman.