She was "just a great, fun presence of a person," said Hagen Engler, former editor of the magazine FHM. He described her as "a bikini model, beautiful, gorgeous girl" with a "wicked" sense of humor. She understood the industry and was intelligent and fun to work with, he said.
Pistorius' father, Henke, told the South African Broadcasting Corp. his son was "sad at the moment."
"I don't know nothing. It will be extremely obnoxious and rude to speculate," the father said. "I don't know the facts."
Nike pulls ad
Nike pulled an ad featuring Pistorius from its website Thursday. The ad showed Pistorius taking off for a run, and contained the words" I am the bullet in the chamber."
The company issued a statement expressing "sympathy and condolences to the families concerned following this tragic incident." The company added that it will not comment further, noting that the situation is a police matter.
Other Pistorius sponsors -- including prosthetics manufacturer Ossur, British Telecom, and Oakley, which makes sunglasses and other products -- expressed condolences and said they had no further comment at this time. Fashion company Thierry Mugler had no comment.
As Olympian, Pistorius faced controversy
Pistorius, a double amputee, competed against able-bodied runners during the London Olympics, triggering controversy as some said the prosthetic limbs gave him an advantage. His legs were amputated below the knee when he was a toddler because of a bone defect. He runs on special carbon fiber blades.
Pistorius was initially refused permission to enter the Olympics, but he hired a legal team to prove that his artificial limbs did not give him an unfair advantage -- and was allowed to compete.
While he did not win a medal, his presence on the track was lauded by many people around the world as an example of victory over adversity and dedication to a goal.
He smashed a Paralympic record to win the men's 400m T44 in the final athletics event of the 2012 Games.
In an October interview with CNN's "Piers Morgan Tonight," Pistorius discussed the "massive blessing" of inspiring people around the world.
"Being an international sportsman, there's a lot of responsibility that comes with that, so having to toggle that and remembering, you know, that there are kids out there, especially, that look up to you -- it's definitely something that you need to keep at the back of your mind."