Some of the text messages exchanged between Oscar Pistorius and Reeva Steenkamp indicate their relationship had elements of emotional abuse, criminologist Elizabeth Grobler says.
Grobler, who works with parole boards on criminological assessments of offenders, has been particularly struck by messages showing Pistorius got angry over Steenkamp talking to another man - an old friend of hers - at a party without introducing him to the athlete.
Pistorius forced Steenkamp to leave the party, leaving her feeling upset and scared.
"That sort of abuse is caused by individual characteristics such as poor self-esteem, insecurity and fear of being rejected, which are present in Oscar," Grobler told DPA by telephone.
"A sense of inadequacy and jealousy are often masked by egotism, arrogance and aggression. Pistorius' disability (is something that) would make him insecure."
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The text messages also show Steenkamp often "acted like a victim, trying to please him, make him happy and feed his ego".
Pistorius's allegedly reckless handling of guns is another warning sign, Grobler said. Killings are often preceded by such behaviour, which "may escalate".
Most of the text messages, however, reflect a loving relationship, the expert said.
It is too early to draw any conclusions about why Pistorius killed his girlfriend, Grobler stressed. "Only Oscar knows what happened that night," she added.
