Oscar Pistorius has yet to testify in his murder trial. That will change next week, when the South African sprinter takes the stand.

The Olympian is expected to speak about the murder of Reeva Steenkamp on Tuesday or Wednesday, according to CNN. Pistorius has admitted to shooting and killing his girlfriend, though he claims he mistook her for an intruder.

When Pistorius takes the stand, he’ll likely be asked to clarify his recollection of the night in question. Several of his statements immediately following the alleged murder have been called into question throughout the case.

After Steenkamp was killed, Pistorius told authorities that he thought his girlfriend was still in bed when he shot her through the bathroom door. Testimony from a ballistics expert, though, suggests Pistorius would have heard the model screaming after the first few shots. Capt. Christian Mangena says the bullet to Steenkamp’s head, which likely killed her instantly, hit her last. The other two shots that hit Steenkamp connected with her arm and hip.

Earlier in the trial, neighbors testified to hearing the screams of a woman. Witness Michelle Burger told the court she heard the shots fired after Steenkamp had yelled. The defense claims those were the high-pitched screams of Pistorius, who was calling for help.

Pistorius’s timeline of events has also been discredited by experts. The 27-year-old claims that on Valentine’s Day 2013, he and his girlfriend were in the bedroom by 10 p.m. Pathologist Gert Saayman performed the autopsy on Steenkamp, and testified that the model probably had her last meal around 1 a.m. Capt. Francois Moller presented evidence claiming Steenkamp’s iPhone was used hours after Pistorius says the two went to bed.

Despite indications that much of Pistorius’s story may be false, the sprinter contends that he had no intention of shooting his girlfriend. In the courtroom, he’s had multiple emotional displays, crying and even vomiting when Steenkamp’s death was described in detail.

Defense attorney Barry Roux is looking to keep Pistorius out of prison. He’s had a few contentious exchanges with those who have disputed his client’s claims.