A ballistics expert called Thursday to testify by Oscar Pistorius' defense offered a different explanation to prosecutors for one of the wounds sustained by Reeva Steenkamp when she was shot and killed by the world-famous athlete last year.

Wollie Wolmarans testified his reconstructions of the Feb. 14, 2013 shooting showed that the pattern of wood splinter marks around a gunshot wound on Steenkamp's right arm indicated that the arm was between six and 20 centimeters from a wood toilet door when it was hit by one of four hollow point bullets fired through the door by Pistorius.

Wolmarans' testimony differed with a police ballistics expert, who said earlier at Pistorius' murder trial that the wound was suffered by Pistorius' girlfriend further away from the closed door as she fell back in the toilet cubicle and protectively covered her head with her arms. Steenkamp was shot in the hip, arm and head.

Wolmarans' opinion was being used by the defense to show that Steenkamp may have been reaching out with her arm to open the cubicle door when she was hit. That assertion is in contrast to prosecutors' claims that the model was hiding in fear of an angry Pistorius during a heated nighttime argument.

He was the third witness called by the defense Thursday as it continued to paint a picture of the Valentine's Day shooting as a tragic error by Pistorius, who claims he fired in fear at a perceived intruder in the cubicle and was devastated by his fatal mistake afterward. The double-amputee runner is charged with premeditated murder for Steenkamp's death and faces 25 years to life in prison if convicted. He sat hunched forward with his head in his hands during much of Wolmarans' testimony.

The defense earlier called a social worker and probation officer who said she spoke with Pistorius in a police cell a day after the shooting last February. Yvette van Schalkwyk described the Olympian as traumatized and grieving for his slain girlfriend and concerned about her parents.

"I saw a heartbroken man. He cried 80 percent of the time," van Schalkwyk said of her meeting with Pistorius on Feb. 15, 2013. She told the court that she decided to testify because she was upset by suggestions reported in the media that Pistorius was feigning grief to sway the judge in his favor. Her testimony was unexpected and she said she had only contacted Pistorius' lawyers on Tuesday. (AP)