Superintendent Piet Byleveld may call himself a "boereseun from Nylstroom" but he has one of the most enviable success rates in solving serial murders in the world.

The 54-year-old, who works with a small team of officers, compared with the dozens assigned to similar cases overseas, has solved every serial murder on which he has worked since 1996.

Overseas investigators, including Scotland Yard detectives in London, often call him for advice.

On Wednesday the official co-ordinator of serial murders and rapes in Gauteng took time off to give some insight into the minds of serial killers and his own motivation for tracking them down.

When he matriculated in 1968, he intended to become a church minister. But during his year of compulsory army service, his goal changed.

"In my ninth month of service I called my father and told him to cancel all the university plans because I wanted to be a police officer," Byleveld said.

"He was disappointed at first, but to be a minister or a police officer is the same thing. You work with the community, and I am proud to be a police officer."

His successes in capturing criminals have served to make him one of South Africa's most recognised police officers.

He has chalked up successes like Cleveland serial killer Moses Sithole, Nasrec serial killer Lazarus Mazingane, Wemmer Pan serial killer Cedric Maake - who stalked and killed couples at Wemmer Pan and bludgeoned city tailors with a hammer - and Bruma Lake killers Themba Nkosi and Simon Majola.

"I can't handle these people killing innocent people, especially women. It is the most terrible thing for a woman to be terrorised in that way," Byleveld said.

Known for not taking leave in the past seven years, the top cop says he can't stop working or retire.

"If I retire I'll die within a week. I can't sit around, I have to be active."

The longest-serving officer in the murder and robbery squad, now known as the Serious and Violent Crime Unit, Byleveld said he hated to sleep, was always restless, and after 30 years of marriage had no children "because I am hardly at home".

Recounting one of his earlier cases - that of Kranskop serial killer Bongani Mseka, who strangled women and bashed in their heads - Byleveld said Mseka was the only killer he had arrested who pleaded guilty to the charges.

"What surprised me was that he asked me to testify on his behalf. I thought this strange, but then he called and said he wanted to meet me in his cells."

"He begged me to tell the court not to ever release him, because if they did he would kill again."

Byleveld said it was his experience that a serial killer would continue to murder if let out of jail.

Although he used psychological profilers to help in his investigations, the best method was to think like the killers to track them down.

"I have to think like them I have something in me that I can't explain which helps."

Byleveld said one of the most important reasons for his successful conviction rate was his determination to follow all his cases through to trial.

It was extremely important not to leave a case with the prosecutor, but to work closely with them through each step of the trial.

"The public have an incorrect perception that as soon as a guy is arrested, that is where the investigation stops."

"My investigation stops as soon as the judge finds them guilty," Byleveld pointed out.

Despite his unassuming appearance, he admitted he was affected by the cases he investigated.

"Sometimes after a conviction you have to take time to think things over. Yes, there are always things that worry you," Byleveld said.

The man who made an arrest in the Leigh Matthews case won't give up.

"Just give me a tough case, and don't tell me 'You're not going to solve it'. I have lost before, but not since 1996," he said.