The way in which Andrew Chimboza killed a man and removed his heart could be classified as aggressive mutilation, a psychologist told the Western Cape High Court on Monday.

"What happens in these cases is that there is complete mutilation and rage. It is an overkill; more violence than necessary to achieve the goal," Major Hayden Knibbs testified.

"This behaviour is an attempt to completely obliterate the object...."

Knibbs is a chief clinical psychologist within the SA Police Service's investigative psychology unit.

He compiled a report to provide Judge Ashley Binns-Ward with insight into Chimboza's behaviour for the purposes of sentencing.

Knibbs classified the killing of 62-year-old Mbuyiselo Manona last year as an extreme form of aggressive mutilation.

He said this type of mutilation was an emotional response of some sort, whether it be frustration or an insult.

Published studies on mutilation seemed to suggest that a number of perpetrators were psychotic or had a low level of intellectual functioning.

Knibbs said neither applied in this matter, since there was no sign of psychiatric illness and Chimboza was educated.

Chimboza, who moved to Cape Town from Zimbabwe six years ago, recently pleaded guilty to the killing as part of a plea agreement.

In an explanation of plea, he said he stabbed Manona to death at the home of a former client last June, after a disagreement.

He alleged Manona attacked him with a knife. He retaliated by kicking him in the groin, stabbing him in the neck with a fork, and then repeatedly stabbing him in the neck, chest, and abdomen with a knife.

Manona was his ex-client's lover, and had apparently accused Chimboza of having sex with his partner.

The accounts of the arresting officer, a forensic pathologist, and a Gugulethu resident during sentencing arguments all seemed to point to Chimboza removing Manona's heart, cutting it up in pieces, and eating it.

Manona died from incisions to the neck, chest and abdomen, and blunt force injuries.

Chimboza's lawyer Yasmine Rajap denied that he had eaten pieces of the heart.