(CNN) -- South African Olympian Oscar Pistorius is on trial for the murder of his girlfriend, model Reeva Steenkamp, at his Pretoria home last year.
Prosecutors say Pistorius murdered Steenkamp in cold blood following an argument in the early hours of Valentine's Day in 2013. The track star says he mistook her for an intruder.
South Africa's "trial of the century" began in March but was delayed for six weeks so Pistorius could be submitted for a psychiatric evaluation. As the trial resumes, reacquaint yourself with the basics and find out what might happen next.
What is Oscar Pistorius charged with?
In addition to being accused of the premeditated murder of his girlfriend, Pistorius also faces a gun charge related to the killing, along with two additional gun-related charges for two separate instances of firing a gun in a public space before the killing.
Why is Pistorius facing a judge rather than a jury trial?
South Africa abolished jury trials in 1969, while the country was under apartheid, due to fears of racial prejudice by white jurors. Pistorius is being tried in Pretoria by Thokozile Matilda Masipa -- the second black woman appointed to the bench since apartheid ended.
What are the sentencing guidelines for premeditated murder?
For premeditated murder, the mandatory sentence in South Africa is a life sentence, which in practice is 25 years unless someone can prove extraordinary circumstances.
Extraordinary circumstances could include a combination of number of factors: for example, that it was a first offense, the age of the person and in Pistorius' case, his disability and the impact this could have had on his actions.
James Grant, senior lecturer in criminal law at South Africa's University of the Witwatersrand, said if the court accepted the prosecution's case -- that Pistorius chased Steenkamp into the bathroom and "hunted" her down -- the track star's defense team would be hard-pressed to convince the court that there should be any considerations that should override the repugnance that should be felt.
What happens if Pistorius is found not guilty of premeditated murder?
If Pistorius is found not guilty, he would face a "competent verdict" or lesser charge of culpable homicide, which is based on negligence.
Pistorius is not claiming self-defense; he is claiming to have been mistaken about his need for self-defense. He is denying that he intentionally unlawfully killed Steenkamp. Grant said the defense boiled down to Pistorius saying "I made a mistake."
If the court were to rule that the mistake was unreasonable -- based on what an objective, ordinary South African would do in the circumstances of the accused -- he would be found guilty of culpable homicide.
Grant said he would expect a court to probably conclude that it is unreasonable to fire at anybody through a closed door regardless of whether they were an intruder, because of the value of human life.
"I'm expecting that if he beats the murder charge, he is in very grave jeopardy of being convicted of culpable homicide," he said.
What's the sentence if Pistorius is convicted of the lesser charge of culpable homicide?
If Pistorius is convicted of culpable homicide, no minimum sentencing legislation would be triggered. "Courts are able to exercise their complete and ordinary discretion," Grant said.
This means, theoretically, Pistorius could get a non-custodial sentence if convicted of culpable homicide. Grant said there had been examples of people killing a loved one accidentally where they had avoided jail.
If, however, the court took a view that Pistorius had been grossly negligent, Grant said, he would guess the runner could be jailed for up to 15 years.
What about appeals?
If Pistorius is convicted, he could potentially appeal to the supreme court and even eventually to South Africa's constitutional court.
If the initial court did not give him leave to appeal, he could petition South Africa's chief justice for permission.
The right to appeal depends on whether, based on the facts of the case, the initial judge or magistrate believes a different court could possibly reach a different verdict.
South Africa's highest court, the constitutional court, used to be only for cases regarding constitutional matters, but a recent act of parliament broadened its remit.
How much longer will the trial last?
When court resumes, there are five steps left in the case: the defense needs to finish with its witnesses, both sides will present their closing arguments, the judge will set a date to render her verdict, there will be a mitigation of sentence phase if Pistorius is found guilty of anything, and then the judge will deliver the final word on a sentence. If Pistorius is convicted on any of the charges, we could see a sentencing date as soon as the end of July.
How damaging was Pistorius' cross examination by the prosecution?
The sprinter's testimony could be key to the outcome of the trial. Prosecutor Gerrie Nel hammered away at Pistorius' version of events during a gruelling five-day cross-examination, but from a legal perspective it's too soon to tell whether that's enough to swing the case either way. His testimony will be considered by the judge and assessors in light of all the evidence presented at the trial, and we don't yet know what aspects of his testimony will be supported by any subsequent evidence presented by the defense's remaining expert witnesses, who are yet to testify.
We do know what holes Nel was trying to poke in Pistorius' case, though. For example, he claims that aspects of Pistorius' version of events on the night of Steenkamp's death are so improbable they can't possibly be true.
Nel has also suggested that the additional information which Pistorius mentioned for the first time at trial -- rather than in his earlier bail affidavit -- is evidence that he is lying and making up his version as he goes along.
Whether the judge ends up agreeing with Nel's assertions will depend on how they fare in comparison to the rest of the evidence presented during the trial.
Did Pistorius change his defense on the stand? What's the legal difference between "it was an accident" and "I pulled the trigger by accident?"
Pistorius has always argued "Putative Private Defense." In layman's terms this means "I genuinely, but mistakenly, believed I was acting in self-defense."
Describing the killing as "an accident" is not necessarily incongruous with this. In other words, "I killed Reeva by accident, or by mistake." This explains why Barry Roux, the lead defense lawyer, asked Pistorius during the sprinter's re-examination what he had meant by "accident" -- and Pistorius intimated that the whole outcome of the night, that is, the death of his girlfriend, was an accident.
If he says "I pulled the trigger by accident" this is a different defense -- the defense of "Automatism or Involuntary Conduct."
The legal definition of voluntary conduct is that the accused's conduct was governed by his conscious free will. Where his conduct is not controlled by his conscious mind, the conduct will be involuntary and the accused will be acquitted. If he says "I pulled the trigger by accident" then the conduct was not voluntary, as his mind was not applied to it -- for example, "my finger slipped and the gun went off."
Previously during his cross-examination, Pistorius told Nel that the gun went off by accident, which is why Nel continued to pursue that line of questioning, providing Pistorius with the opportunity to place on record that he was changing his defense.
Pistorius is skating close to the line of changing his defense but has not quite crossed it -- yet. He ended his testimony by clearly stating "it was an accident," which can still be read in line with the Putative Private Defense. Nonetheless, jumping from one contention to the other is unlikely to leave a positive impression in the minds of the judge and assessors.
Why was the defense's re-examination of Pistorius so short?
Roux adopted the opposite strategy of that adopted by Nel; whereas Nel kept Pistorius on the stand for as long as possible, jumping between different lines of questioning, providing opportunities for Pistorius to confuse his version of events and expose inconsistencies in his testimony, Roux needed to keep it short and sharp, simply focussing on the core parts of the defense case that he believes undermine the state's case.
This conciseness was designed to elicit clear answers from the witness and to clarify certain key issues in the mind of the judge and assessors. The subject matter Roux chose to cover -- the screams, allegations of crime-scene contamination, the independence of Pistorius' bail affidavit and the loving message on the Valentine's card Steenkamp wrote to Pistorius -- all strike at the core of the state's case.
Where does this leave us?
We now have a clear narrative of the state's version placed on the court record. Their version of events is that Pistorius and Steenkamp had a heated fight in the bedroom, she fled from him, screaming in terror, locked herself in the toilet for protection and that Pistorius chased her down and intentionally shot and killed her. They have tested this version against Pistorius' testimony through cross-examination.
The defense will continue to test the state's version of events through their remaining expert witnesses. At the end of the defense's case both sides will present closing arguments in a final attempt to convince the judge and assessors why their case is more reliable and persuasive. Ultimately, it will be up to the judge and assessors to decide whether the state has met their burden of proof.
Is Pistorius done, or can the defense bring him back up at some point to clarify some answers?
Pistorius is done testifying now. He can only be recalled if new evidence is found. Witnesses only get one chance to put their testimony on record, otherwise it would be too easy for any witness to tailor their evidence. It is the same rationale behind the rule that once a witness begins testifying they cannot be in contact with the legal team for whom they are giving evidence.
Are there restrictions on reporting any aspects of the trial?
Yes. In South Africa anyone can be found guilty of contempt of court if for impugning the dignity of judicial proceedings, interfering with the accused's right to a fair trial, or scandalizing the criminal justice system, according to CNN legal expert Kelly Phelps.
Phelps said one big difference when it comes to contempt of court is the fact a single judge will be presiding over the case, rather than a jury. "It's believed that judges are cloaked in the letter of the law and have an ethical and professional responsibility to apply the law in a fair and impartial manner, and that means this risk of reporting influencing a trial is less in this system than in a jury system."
But unlike in a jury system, where juries often only have to issue a verdict -- and not declare the reasons for their decision -- the judge is required by law to issue clear reasons for the verdict. "If it were apparent in those reasons that there did appear to be a lack of impartiality due to media influence, there's recourse to an accused person," said Phelps.
Would Pistorius be given special treatment in prison if he was convicted and jailed?
CNN's team in Johannesburg understands the double amputee would not receive special treatment, with even blind prisoners being placed with sighted prisoners in South Africa.
But, ahead of his release on bail last year, the African National Congress Women's League said the athlete had in fact benefited from special privileges, adding that his family could visit him outside visiting hours, unlike relatives of other inmates.
What is the reputation of South Africa's legal system?
James Grant said that South Africa was proud of its constitution and had a well-respected judiciary and that its substantive criminal law was "similarly advanced and progressive and very well considered."
"The problems that we're facing are more of a systemic procedural nature.
"We have an incredibly strained police force that's not particularly well-trained -- they're massively overloaded -- and we're struggling with issues of corruption within the police force and possibly even within the prosecution service," he said.
Grant said that, regrettably, wealthier South Africans had access to better legal resources than most of their compatriots.
"Unfortunately, most South Africans don't have that extent of resources available to them. They wouldn't have available to them the best possible defense lawyers, but in a strange sense, this is not a problem unique to South Africa. Money buys for you a degree of protection. That's of course a universal problem."
In March of last year, the South African government's midterm report noted that "The effectiveness and ability of the criminal justice system to serve as a deterrent against crime is unfortunately still under threat of being undermined by the actions of a small number of those who serve in it."
It continued: "Since 2009, investigations have uncovered 1,529 persons in the criminal justice system who were possibly involved in corruption-related crime."
What are conditions like in South African jails?
South Africa's jails were put under the spotlight during the extradition hearing of Shrien Dewani, the Briton who stands accused of ordering a hitman to murder his new wife in 2010.
One of the defense's arguments -- not upheld -- against extradition was that Dewani would not be safe in South African custody.
His lawyer quoted figures from a South African report suggesting that almost half of prisoners believed sexual abuse was a feature of life in South African jails. But Dewani's request for Britain to block his extradition was declined in January of this year, and he has now appealed the decision to Britain's highest court.
Nooshin Erfani-Ghadimi, project coordinator for the Johannesburg-based Wits Justice Project, told CNN that South Africa's constitution and its bill of rights with regards to prisoners' rights were among the best in the world.
However, she said, overcrowding meant "unfortunately that doesn't necessarily translate into practice."
"A legacy of apartheid is that prison cells are still unfortunately a place where prisoners can be abused," Erfani-Ghadimi said.
South African public broadcaster SABC cited the Correctional Services Department as saying prisoners with disabilities were treated with dignity and enjoyed the same rights as able-bodied inmates.
However, a "statement of agreed factual findings" in the case of inmate Dudley Lee -- who contracted tuberculosis while imprisoned -- may point to a different reality. Lee said he "begged, bullied and bribed" to get the medication he needed.
CNN's Brian Walker and Richard Greene contributed to this report.