JOHANNESBURG — The family of Oscar Pistorius’s slain girlfriend wants answers, her mother told a Johannesburg newspaper, as South Africans braced to hear why prosecutors believe a national hero murdered the model who was shot multiple times.

June Steenkamp, Reeva Steenkamp’s mother, told The Times in a front page interview published Monday: ‘‘Why? Why my little girl? Why did this happen? Why did he do this?’’