HARDUS Lotter knew that killing his parents was wrong, the Durban High Court heard yesterday.

"He knew what he was doing was wrong, but he couldn't resist carrying out the murder. He thought he was doing God's work," clinical psychologist Laurens Schlebusch said.

Schlebusch said Hardus believed he had to be a participant in his parents' murders to save the world.

Hardus, 23, his sister Nicolette, 29, and her ex-boyfriend Mathew Naidoo, 25, stand accused of murdering the siblings' parents.

Maria Magdalena "Rickie" Lotter, 52, and Johannes Petrus "Johnny" Lotter, 53, were killed in July 2008.

The Lotters claim Naidoo masterminded the murders and justified them by saying they were God's will. On Wednesday, Nicolette testified Naidoo used "witchcraft" to compel her and her brother to kill their parents. She also felt "indebted" to him because he had helped her spiritually.

Schlebusch yesterday described Hardus as a loner because he did not have any friends.

"He was teased at school. They called him sleepy head and tortoise. This affected his self-esteem."

Schlebusch said Hardus had a poor self-image, was shy, sensitive and withdrawn.

"This made him vulnerable and affected him emotionally because he thought he was not worthy."

His loneliness made him vulnerable to the influence of Naidoo and his sister.

"His sister's involvement exacerbated the situation because he looked up to her," Schlebusch said. He called the type of influence Naidoo and Nicolette had on Hardus "coercive persuasion".

"This is done by reprogramming someone's thinking, by breaking down their beliefs and introducing a new belief system."

Schlebusch said this was done by rituals performed by Naidoo, who claimed to be the third son of God.

"At the time, he (Hardus) was trapped in an abnormal religious belief system. He believed he was doing the right thing."

Hardus broke all mental connections with his past to commit the murder. Schlebusch said there had been other cases around the world where someone was influenced to kill. This was often done by an intelligent and charismatic individual.

Hardus had a normal upbringing and no history of violence. He expressed severe remorse for his involvement in the murder when he broke down in tears during a consultation.

Hardus suffered from depression before and after his parents' murder.

He also suffered post-traumatic stress, caused by the role he had played in the murder. - Sapa