Sword killer Morne Harmse may not have been a practising satanist, but he was dabbling in the occult.

This was according to satanism expert Dr Kobus Jonker, who testified this morning in the pre-sentencing hearing of the teenager who went on the rampage with a ninja sword at his school last year, killing a fellow pupil.

He took the stand as the expert witness called by the court.

Jonker, a retired policeman, said he had established the police's occult-related crimes unit after being told to look into the issue by former minister of law and order Adriaan Vlok.

Between 1981 and 2000, Jonker investigated hundreds of occult-related crimes and testified in 30 to 40 murder cases.

This earned him several nicknames, including "Donker Jonker", "The Hound of God" and "God's Detective".

His unit was disbanded after human rights groups claimed that it was not constitutional in a country that guaranteed religious freedom.

He has written two books on the subject of satanism in South Africa.

Testifying this morning, Jonker said he had interviewed Harmse on August 17.

Jonker described the crime, which Harmse has confessed to, as a purposeful and planned attack that did not fit in with what he knew to be a satanic or ritual murder.

But Harmse appeared to have experimented with satanism and witchcraft, he said.

Commenting on photographs of Harmse's bedroom, Jonker said the room lacked elements one would have expected to see had the teenager been a practising satanist.

"One would expect to find an altar of sorts, red and black candles and demonic posters," he said. Satanists apparently use black candles to draw on the power of darkness and red for the energy of blood.

Jonker said there were no blood smears on the wall as would generally be seen in cases where practising satanists entered into devilish acts. He noted that a dragon poster on the teenager's wall was more in line with eastern religion than satanism.

Jonker told the court that there was a wooden table in the corner of the room and a human figure surrounded by circles had been etched into the wood.

Harmse had told him that this was a demon that could help him do things with animals and plants. Jonker had never seen that image before, but was told that Harmse had got it off the internet.

He said a diary in the room contained some kind of witches' scripts. These he also did not recognise, but believed that they had been taken off the internet.

A homemade ouija board had been hidden under Harmse's bed, he said. Often, satanists use such a board to summon demons.

But white, pink and yellow candle wax on the board showed that it had not been used for satanic rituals, in which only black and red candles would have been used.

This showed that Harmse did not really know about this, and was merely playing with the board.

The hearing continues.