South Africans were shocked at the killing. But while Pistorius captured the nation's attention with his Olympic quest, police said there was a recent history of problems involving him. Police spokeswoman Brigadier Denise Beukes said the incidents included "allegations of a domestic nature."
"I'm not going to elaborate on it but there have been incidents (at Pistorius' home)," Beukes said. Police in South Africa do not name suspects in crimes until they have appeared in court but Beukes said that the 26-year-old Pistorius was at his home at the time of the death of Steenkamp and "there is no other suspect involved."
Pistorius' father, Henke, declined to comment when contacted by The Associated Press, only saying "we all pray for guidance and strength for Oscar and the lady's parents."
Neither Pistorius' agent Peet van Zyl nor coach Ampie Louw could be reached while Pistorius' own cellphone went straight to voicemail.
Pistorius' former coach, Andrea Gianni, said he hopes it was "just a tragic accident." Gianni said he believed that Pistorius had been dating Steenkamp for "a few months."
"No matter how bad the situation was, Oscar always stayed calm and positive," Gianni told the AP in Italy. "Whenever he was tired or nervous he was still extremely nice to people. I never saw him violent."
Yet Pistorius had troubles in his personal life. In February 2009, he crashed a speed boat he was piloting on South Africa's Vaal River. Witnesses said he had been drinking before the crash and officers found alcoholic beverages in the wreckage, though they acknowledged at the time they hadn't conducted a blood test on the athlete. Pistorius broke his nose, jaw and several ribs in the crash, as well as damaged his eye socket and required some 180 stitches to his face.
In November, Pistorius also found himself in an altercation with a local coal mining millionaire over a woman, South African media reported. Eventually, the two men involved the South African Police Service's elite Hawks investigative unit before settling the matter.
Pistorius owned firearms and posted a photograph of himself at a shooting range in November 2011 to the social media website Twitter, bragging about his score.
"Had a 96% headshot over 300m from 50shots! Bam!" he tweeted.
Police said that earlier reports that Steenkamp may have been mistaken for a burglar by Pistorius did not come from the police. Several local media outlets initially reported that the shooting may have been accidental.
Capacity Relations, a talent management firm, earlier named model Steenkamp as the victim of the shooting. Police spokeswoman Lt. Col. Katlego Mogale told the AP that officers received a call around 3 a.m. after the shooting.
A 9 mm pistol was recovered and a murder case opened against Pistorius.
Pistorius enjoyed target shooting with his pistol and an online advertisement featuring him for Nike read: "I am a bullet in the chamber." An article in January 2012 in The New York Times Magazine described him talking about how he pulled a pistol to search his home when his alarm went off the night before an interview. At Pistorius' suggestion, he and the journalist went to a nearby target range where they fired at targets with a 9 mm pistol. At one point, Pistorius told the writer: "If you practiced, I think you could be pretty deadly."
Asked how often he went target shooting, Pistorius replied: "Just sometimes when I can't sleep."
Police have still not released the name of the woman, but the publicist for Steenkamp confirmed in a statement that the model was dead.
"We can confirm that Reeva Steenkamp has passed away," Steenkamp's publicist Sarit Tomlinson said. "Our thoughts and prayers go to the Steenkamp family, who have asked to have their privacy respected during this difficult time, everyone is simply devastated. She was the kindest, sweetest human being; an angel on earth and will be sorely missed."
Tomlinson said Steenkamp, known simply as Reeva, was one of FHM's (formerly For Him Magazine) 100 Sexiest Women in the World for two years running, appeared in countless international and national advertisements and was one of the celebrity contestants on the reality show "Tropika Island of Treasure," filmed in Jamaica.
On Twitter, she tweeted messages urging women to stand up against rape as well as her excitement about Valentine's Day. "What do you have up your sleeve for your love tomorrow?" she tweeted. "It should be a day of love for everyone."
Pistorius made history in London last year when he became the first double-amputee track athlete to compete in the Olympic Games, propelling him to the status of an athletics superstar.
Having had both his legs amputated below the knee before his first birthday because of a congenital condition, he campaigned for years to be allowed to compete against able-bodied athletes. Having initially been banned because of his carbon fiber blades which critics said gave him an unfair advantage he was cleared by sport's highest court in 2008 and allowed to run at the top events.
He competed in the 400 meters and on South Africa's 4x400 relay team at the London Games, making history when his selection for South Africa's team was confirmed at the very last minute. He also retained his Paralympic title in the 400 meters in London.
South Africa's Sports Confederation and Olympic committee released a statement on Thursday saying they had been "inundated" with requests for comment but were not in a position to give out any details of the shooting. The International Paralympic Committee also said it wouldn't comment in detail apart from offering its condolences to the victim's family.
South Africa has some of the world's highest murder rates, with nearly 50 people killed each day in the nation of 50 million. It also has high rates of rape, other assaults, robbery and carjackings.
U.N. statistics show South Africa has the second highest rate of shooting deaths in the world, second only to Colombia.
"The question is: Why does this story make the news? Yes, because they are both celebrities, but this is happening on every single day in South Africa," said Adele Kirsten, a member of Gun Free South Africa. "We have thousands of people killed annually by gun violence in our country. So the anger is about that it is preventable."
Imray reported from Cape Town, South Africa. Associated Press writer Michelle Faul contributed to this report from Johannesburg.
Pistorius Twitter feed is 1 long victory lap
Since captivating the world with his groundbreaking Olympic trip to London, Oscar Pistorius' life has seemed like an extended victory lap.
More than 230,000 Twitter followers have been given a glimpse into a life of fast cars and luxury holidays as the hero was feted by an adoring public. The "Blade Runner" has reveled in the fame that came from becoming the first amputee sprinter to compete at both the Olympics and Paralympics.
Among dozens of tweets in recent weeks, there are only a scattering of references to the girlfriend he is now accused of killing earlier Thursday.
Quoting a tweet from Reeva Steenkamp on Dec. 6 "Wondering what my stalker is up to? Kinda miss him lurking around 2nyt" Pistorius replies: "Heard he is taking a water break with the boys!;)" Pistorius' girlfriend was a model, law graduate
The woman shot dead in double-amputee Olympian runner Oscar Pistorius' house was a model, a law school graduate and an entrepreneur committed to empowering women.
Reeva Steenkamp was to give an inspirational talk Thursday at a Johannesburg school.
Steenkamp had become a celebrity in her own right, said Publicist Sarit Tomlinson. She was one of FHM magazine's 100 Sexiest Women in the World for two years running, appeared in international and South African advertisements and was a celebrity contestant on Tropika Island of Treasure filmed in Jamaica. She was also the South African face of Avon cosmetics.
The freckled blonde who appeared in scanty bikinis on magazine covers and sashayed down the world's fashion ramps was "continuously breaking the model stereotype," said Tomlinson.
Steenkamp was "the sweetest, kindest, just angelic soul" and at the same time "a very inspiring individual, very passionate about speaking about women and empowerment."
Police said she was shot by four bullets in the early hours of Valentine Day. They said only Steenkamp and Pistorius were at his house in a gated complex in Pretoria, the capital. Police have arrested Pistorius on a charge of murder and said he will appear in court Friday. The two had been dating for a few months.
Scores of tributes were posted online. Her publicist said Steenkamp was 29 but police said she was 30.
Thursday morning, Steenkamp had been scheduled to give a motivational speech to school students in Johannesburg. "It was about empowerment and inspiration and what inspires you and how to follow your dreams," said Tomlinson, who had Steenkamp's notes for the speech.
On Twitter, Steenkamp tweeted messages urging women to stand up against rape as well as her excitement about Valentine's Day.
"What do you have up your sleeve for your love tomorrow?" she tweeted. "It should be a day of love for everyone."
Her last tweet was an enthusiastic acceptance of a friend's invite to celebrate the day with chocolate cupcakes topped with red hearts.
She also used her Twitter account to encourage her thousands of followers to fight sexual abuse.
"WEAR BLACK THIS FRIDAY IN SUPPORT AGAINST #RAPE," she re-tweeted just hours before she died.
Steenkamp urged followers to stand up against violence against women, tweeting four days ago as South Africa was outraged by the particularly brutal rape and murder of a 17-year-old: "I woke up in a happy safe home this morning. Not everyone did. Speak out against the rape of individuals in SA (South Africa). RIP Anene Booysen #rape #crime #sayNO."