PRETORIA, South Africa (AP) — More than a year after he killed his girlfriend, Oscar Pistorius is expected to finally answer questions about why he shot Reeva Steenkamp through a toilet door when his murder trial resumes this week and his defense lawyers begin presenting the evidence they hope will save the Olympic athlete from going to prison for 25 years to life.

Pistorius’ account that he killed Steenkamp by mistake is going to “stand or fall” with his testimony in court, a legal expert says.