A forensic psychiatrist testifying for the defense told the Oscar Pistorius murder trial on Monday that the double amputee track star suffered from an “anxiety disorder” after growing up with a mostly absent father and a mother so afraid of intruders that she slept with a firearm under her pillow.

The testimony by the psychiatrist, Merryll Vorster, offered an uneasy echo of Mr. Pistorius’s own account of events in his bedroom in the early hours of Feb. 14, 2013, when he has admitted taking a handgun and firing four shots through a locked bathroom door, killing his girlfriend, Reeva Steenkamp, a 29-year-old model and law graduate.

Under cross-examination by prosecutor Gerrie Nel, Ms. Vorster said Mr. Pistorius’s perceived disorder did not constitute a mental illness that would require the judge to order a psychiatric examination. But Mr. Nel said the runner should be sent for psychological observation and evaluation to assess whether his mental state was a factor in the killing.

Oscar Pistorius in court in Pretoria on Monday. Testimony is set to end in mid-May, followed by closing arguments and weeks of deliberation before a verdict is issued.Witnesses Tell of Pistorius’s Anguish After Shooting GirlfriendMAY 5, 2014
The prosecution says Mr. Pistorius, 27, murdered Ms. Steenkamp, but the runner says he shot her by accident, believing at least one intruder had entered his comfortable villa in a gated complex in Pretoria, the South African capital, where he is now on trial. The case is being broadcast around the world.
The portrait she offered of Mr. Pistorius’s troubled upbringing and deepening anxieties recalled some of his own behavior during the trial since it opened in early March. On occasions he has wept, wailed, retched and sobbed when confronted with graphic evidence relating to the events surrounding Ms. Steenkamp’s death.

Ms. Vorster, the psychiatrist, said she had interviewed the athlete and some of his family members and friends.

Her testimony seemed designed to bolster the defense’s argument that Mr. Pistorius felt vulnerable because of his disability and had an usually high level of anxiety about intruders. It also seemed intended to rebut earlier prosecution testimony that he was self-centered, trigger-happy, quick-tempered and jealous.

The psychiatrist traced her analysis of Mr. Pistorius’s personality to his birth without fibula bones in his lower legs. At the age of 11 months, both legs were amputated below the knee. The procedure constituted a “traumatic assault” that he would not have comprehended at the time, Ms. Vorster said.

The runner grew up with a mother who was “very anxious,” abused alcohol intermittently and “slept with a firearm under the pillow.” His father was “irresponsible and mostly absent.”