Things had not gone smoothly for him from the moment he was born - in Sandton, Johannesburg on November 22 1986 - without a fibula bone in both his legs, which led his parents to have the limbs amputated below the knee when he was one in order for him not to be confined to a wheelchair.

But less than a month before the Paralympics, Pistorius had exited the London 2012 Olympics in triumph, having become the first amputee runner to compete in the Games after a long and winding road of legal wrangles with the international governing body for athletics, then the International Association of Athletics Federations (IAAF), over whether his prosthetic limbs conferred unfair advantage over able-bodied competitors.

Wavy screen back to 2005... 

A year after he had won the Athens 2004 Paralympic T44 200 metres title in a world-record time, Pistorius was invited by the IAAF to race against able-bodied opponents. School commitments prevented him taking that offer up, but over the next couple of years he began to race against able-bodied opponents more frequently; frequently beating many of them.

On July 13 2007, Pistorius finished second in a B race at Rome's Golden Gala meeting, racing two days later at a rainswept Don Valley Stadium in the British Grand Prix, finishing last in 47.65sec but being disqualified for running outside his lane.

For Pistorius, however, the fire was lit. He was in the frame - and now, having improved his 400m time by four seconds since Athens, he wanted to race at the Beijing 2008 Olympics. But it seemed the IAAF was already having second thoughts.

The South African ran with J-shaped carbon-fibre prostheses called the Flex-Foot Cheetah which had been developed by biomedical engineer Van Phillips and manufactured by Össur.

Marlon Shirley, the American single amputee whom Pistorius defeated over 400m at the Athens Paralympics, complained afterwards that his rival had an unfair "locomotive advantage" with the contraptions fashioned by a team of Icelandic engineers.

By March 2007 there was strong speculation that the IAAF might bring in a precluding rule at a meeting following the World Cross Country Championships in Mombasa.

A few days beforehand I spoke on the topic to Britain's Baroness Tanni Grey-Thompson, the multiple Paralympic wheelchair champion who had retired earlier in the year.

"I have been expecting him to be banned," she said. "When he was running less quickly it was all quite jolly, but as soon as he started running fast times, that's it. I think this has provoked a debate about what it is to be disabled, and what it is to be able-bodied.

"I think there's an argument both ways. People will say that he can pick the length and style of his prosthetics, so maybe that gives him an unfair advantage. I think it's probably more of a disadvantage to be running with two lower limbs missing.

"But others will say if he can be racing against able-bodied runners on two false legs, good luck to him. Oscar is a stunning talent. He is as far ahead of his Paralympic rivals as Michael Johnson was over his Olympic 400m competitors 10 years ago. He has been given a glimpse of inclusion but now it looks like being taken away from him.

"The authorities probably shouldn't have let him compete against able-bodied athletes in the first place. They've given him a chance to get out of the ghetto but they are going to throw him back in again."

On March 26 2007 the IAAF did indeed amend its competition rules to include a ban on the use of "any technical device that incorporates springs, wheels or any other element that provides a user with an advantage over another athlete not using such a device."

The IAAF stated that the amendment was not specifically aimed at Pistorius - but it had already arranged for his performances in Rome and Sheffield to be filmed using high-definition cameras in order to determine how the blades were working for him.

Further tests to which Pistorius submitted in November 2007 were run at the German Sport University Cologne under the guidance of  Peter Brüggemann, a professor of biomechanics, in conjunction with Elio Locatelli, who was responsible for all technical issues in the IAAF. Brüggemann's words to Die Welt were that the results showed "considerable advantages over athletes without prosthetic limbs who were tested by us".

"It was more than just a few percentage points. I did not expect it to be so clear," Brüggemann added.

Based on these findings, on January 4 2008, the IAAF ruled Pistorius' prostheses ineligible for use in competitions conducted under the IAAF rules, including the 2008 Olympic Games.

Pistorius called the decision "premature and highly subjective" and pledged to continue fighting, while his manager, Peet van Zyl, said they would appeal be based on advice from experts in the United States who had said that the report "did not take enough variables into consideration".

On May 16, 2008, the Court of Arbitration for Sport in Lausanne upheld Pistorius' appeal and the IAAF Council decision was revoked with immediate effect.

The CAS panel unanimously determined that Brüggemann had tested Pistorius' biomechanics only at full speed when he was running in a straight line, unlike a real 400m race; that the report did not consider the disadvantages that Pistorius has at the start and acceleration phases of the race; and that overall there was no evidence that he had any net advantage over non-disabled athletes.

Pistorius was free to qualify for the 2008 Olympics - but he could not get the time he needed and so did not go. At the Paralympics he won the T44 100, 200 and 400m titles. And the quest for an Olympic participation went on.

On July 19 2011, Pistorius set a 400m personal best of 45.07sec - inside the World Championship and Olympic A qualifying standard. He ran at the 2011 World Championships in Daugu, reaching the individual 400m semi-finals, and earned a silver medal after running for South Africa's 4x400m relay team in the heats. On July 4 2012, the South African Sports Confederation and Olympic Committee included him in its team for the London 2012 Olympics.

Pistorius duly became the first amputee runner to compete at the Olympics, reaching the individual 400m semi-finals and running the last leg for the relay team as they finished eighth in the final. At the Closing Ceremony he was chosen to carry the South African flag in a stadium to which he would return for the Paralympics that began 17 days later.

The assumption was that Pistorius would complete another clean sweep of Paralympic titles in the 100, 200 and 400m categories. But that did not happen. And that was at least partly down to his pressing ambition to reach the Olympic as well as Paralympic Games.

In his first final on September 2, the men's T44 200m, Pistorius was overhauled over the final 30m and beaten by Brazil's 20-year-old double amputee Alan Oliveira. The crowd, who had acclaimed the South African hugely upon his announcement, were stunned into silence.

Almost as soon as he had crossed the line - you could argue - Pistorius crossed the line and began criticising the size of the blades used by both Oliveira and the American bronze medallist Blake Leeper.

In a trackside Channel 4 interview, Pistorius commented: "The guys' legs are unbelievably long.

"I'm not taking away from Alan's performance. He's a great athlete. But these guys are a lot taller and you can't compete with the stride length. You saw how far he came back. We aren't racing a fair race. I gave it my best.

"The IPC [International Paralympic Committee] have their regulations. The regulations allow that athletes can make themselves unbelievably high. We've tried to address the issue with them in the weeks up to this and it's just been falling on deaf ears.

"You saw Blake Leeper yesterday when the guy came down literally overnight, made his blades longer. His knee height is like four inches higher than it should be. The guys are just running ridiculous times and they're able to do so.

"I think Alan's a great athlete but I run just over 10 metres per second, I don't know how you can come back, watching the replay, from eight metres behind in the last 100m to win. It's absolutely ridiculous."

Craig Spence, spokespereson for the IPC, denied that Oliveira and Leeper had an unfair advantage. "All the blades were measured and there was no infringement of the rules as far as the IPC was concerned," Spence said.

Oliveira, whose winning time of 21.45sec had not matched the world record of 21.30 set by Pistorius in the heats, insisted: "I've been using the same blades all along, for the last five weeks. They were tested. It is training. It is not about two blades. It is about training. I am below the maximum length of blades I could have been.

"I am very happy about having won and all I want to do is thank everybody that helped me get here and celebrate. I am not worried about this polemic that has been raised. This polemic is just about Oscar Pistorius, not about myself. I don't know who he is picking a fight with, it is not with me.

"Pistorius is a big favourite, so when he was announced the whole stadium reacted. When I was announced I realised everyone was silent. I felt like the underdog. He is not a bad loser. He is a great athlete. I am just sad with the interview where he said my blades were too big.

"He was bothered by my time in the semi-finals and he wanted to get to me with his polemic but it did not work. For me, he is a really great idol and to hear that from a great idol is difficult."

The emotional temperature lowered. The following day I was in a big media group that spoke to Pistorius after a heats run. This was a very different Pistorius. He was painstaking in his efforts to answer every question, the model of courtesy. But he did not, essentially, step back from the position he had established the previous night, a position he had reiterated in a meeting with IPC science and medical director Pieter van der Vliet.

London 2012 hardly represented a failure for Pistorius in terms of performance. He did not reach the podium in the 100m but won the 400m title and contributed to South Africa’s 4x100m relay win.

But his comments about his fellow Paralympians had diminished his standing as the standard-bearer, literally in the case of the Olympic Closing Ceremony, for disabled athletes.

In the wake of the row, a number of key facts were re-stated. The IPC insisted it was committed to preventing the use of prostheses that led to an "unrealistic enhancement of stride length".

Since 2007, the IPC has used a formula to calculate the permitted length of prostheses for its athletes. For double amputees such as Pistorius and Oliveira, that was based on measuring each athlete's body and arm span, and using this data to estimate their overall height if they had legs. Athletes were allowed prosthetic limbs and feet that made them up to 3.5 per cent taller than their estimated height including the blade at the end of their prosthesis.

Pistorius was running at 184.5cm but could under the IPC rules extend his prosthesis so he would stand 193.5cm tall. Oliveira was running at 181.0cm but still had leeway to extend to 184.5cm under the IPC's ruling.

The suggestion that Oliveira had won because of a superior stride length appeared to be re-butted by one analysis of the 200m final which claimed that Pistorius had taken 92 steps and Oliveira 98.

As Simon Hart of The Telegraph wrote at the time: "The row over Oliveira’s elongated blades has exposed the sharp divide between disability and able-bodied running because International Paralympic Committee rules permit leg-amputee runners to alter the length of their blades within a certain range to optimise their performance.

"By contrast, the International Association of Athletics Federations offers no such flexibility and has ruled that Pistorius is only eligible to run in able-bodied competition if he uses the same 'Cheetah Flex-Foot' blades that he has worn since he was readmitted into non-disabled competition in 2008…

"All three medallists wore blades supplied by Icelandic company Ossur, and its head prosthetist in the UK, Richard Hirons, confirmed that Paralympic rules allowed athletes to experiment with blade lengths.

"'Oscar could have done it too at the Paralympics, but he didn’t,' said Hirons, who added: 'I think Oscar’s assumption was that longer blades means longer strides and so better times. In actual fact, in sprinting mechanics, turnover and how fast you can bring your legs down is a factor as well.'"

Pistorius would surely not have been able to adapt to a new, longer set of blades in the 17 days that separated the Olympics from the Paralympics.

"Oscar, had he wanted to, could have worn longer blades for the Paralympics. However he decided to stick to the same blade length he had for the Olympics which was dictated to him by the IAAF. For any sprinter to switch between blade length would be tricky," Spence told insidethegames.

Essentially, it seems, Pistorius was paying the price for his Olympic ambition.

Within five months of the London 2012 Paralympics he would be involved in legal wrangling of a far graver nature after shooting his girlfriend Reeva Steenkamp dead at his home in Pretoria.

Pistorius admitted the shooting but insisted he had fired the shots through the toilet door thinking there was an intruder inside.

On October 21 2014, Pistorius received a prison sentence of a maximum of five years for culpable homicide. In June 2015 he was recommended for early release.

South Africa’s Justice Minister, Michael Masutha, said the parole board's decision was "premature", but Pistorius was released from prison on October 19 2015.

On November 3, the Supreme Court of Appeal in Bloemfontein overturned the culpable homicide decision and found Pistorius guilty of murdering Steenkamp.

In the words of justice Eric Leach, one of five presiding judges: "Although he may have been anxious, it is inconceivable that a rational person could have believed he was entitled to fire at this person with a heavy-calibre firearm, without taking even that most elementary precaution of firing a warning shot, which the accused said he elected not to fire as he thought the ricochet might harm him."

On July 6 2016, Pistorius' five-year sentence for culpable homicide was replaced by a six-year sentence for murder, with the anticipation that he would be eligible for release on parole in 2019.

On November 24 2017, the Supreme Court of Appeal increased Pistorius' prison sentence to a further 13 years and five months.

Pistorius appealed against the new sentence in March 2018 - unsuccessfully. He is expected to be eligible for parole some time next year.