http://www.bbc.co.uk/news/world-africa-21455453 Looks like she was sneaking in to give him a Valentine's Day surprise and got more than she bargained for. In his defence Pistorius was legless at the time.
She only asked him to shoot his load over her. The bold Oscar got carried away and took it a bit too far. EDIT - I'm too classy for the obvious leg jokes.
Turns out Pistorius shot her in the head and the upper arm. "Head, shoulders, knees (no toes) knees (no toes)"
I think she's got dressed up like the man from the Milk Tray adds, went a bit too far and blacked up her face and Oscar thought she was a burglar. Either that or he shot her twice at point blank range and has been charged by the SA police with murder. Take your pick.