Forensic expert, Roger Dixon, left, holds a court exhibit, a magazine rack, as he answers questions put to him by chief state prosecutor Gerrie Nel , right, during the murder trial of Oscar Pistorius, in Pretoria, South Africa, Thursday, April 17, 2014. Pistorius is charged with the murder of his girlfriend, Reeva Steenkamp, on Valentines Day in 2013. (AP Photo/Themba Hadebe, Pool)