As the investigators scrambled around the tiny courtroom where Durban businessman Schabir Shaik is being tried, setting up files, organising papers, advocate Billy Downer SC, the leader of the prosecution, stood outside smiling.

"If you have a forensic auditor who knows what he is doing," Downer said, "there is nothing to worry about."

It was a little later that Johan van der Walt took the stand, where he would stay for 16 days - explaining, defending his findings, making jokes and setting out the paper trail on which Downer had based the state's case. Estelle Ellis spoke to him and his assistant, Riaan Beekman.

"I don't stress and I am afraid of nothing," Johan van der Walt says. "The adrenaline sometimes catches up with me, but I sleep well at night.

"My job is to find and communicate the facts. I like being cross-examined. Giving evidence is the ultimate test of my work. If I am proven wrong, I will admit it. I do not get emotionally involved in my cases."

For 16 days during the trial of Durban businessman Schabir Shaik, he was "Mr van der Walt". His calm, professional approach was mirrored by that of Shaik's counsel, Francois van Zyl SC. At the height of their cross-examination battle, their voices became colder and more steely, but the smiles remained.

Van der Walt dropped his files only twice, but managed without fail to find whichever one of the 20-plus behind him held the documents he was looking for.

"The secret," he confided, "was when we realised that the witness stand was too small for our files." He and Anton Steynberg, one of the advocates assisting Downer, fashioned an extended shelf to hold the files. "After that it was easy," he said.

It was with this pragmatic approach that Van der Walt weathered the questions and challenges to his report. By day three of his evidence, people were asking him about his ties: "I hate pretentiousness. I like ties and I like beautiful clothes. I don't work in an industry where people wear overalls." And even though he became the glamour guy of forensic auditing in the past few weeks, Van der Walt said he was just doing his job.

"There are many people who can do this much better than me. Everybody likes recognition, but I think it is much more important to be humble. Respect for me is not something that is coupled with being recognised in the street. I look at someone like my father, who is the most well-read person I know."

After he explained his role to Judge Hilary Squires by saying that he was "a bloodhound", he got stuck with the label.

When Van der Walt's evidence resumed after the evidence of another witness, John Dover, Shaik's brother Mo whispered: "Oh, so now we are going from Dover to Rover."

"It comes from a British court case where the judge had to listen to the evidence of an auditor and a forensic auditor. The judge said that if the auditor was the watchdog, the forensic auditor was the bloodhound - but they are both still dogs,"

Van der Walt laughingly explained. He never meant to become a chartered accountant. The same man, who patiently and with a little smile explained to the court that King II (a report on corporate governance) came after King I, had convinced his lecturers to let him pass Audit III before Audit II. "I was a typical student," Van der Walt said. "It was around then that I realised what I wanted to do."

He subsequently completed an honours degree in accounting at Unisa and a certificate, which is the precursor to writing exams to qualify as a chartered accountant.

"And I did not pass the first time either," Van der Walt said. But he did pass in 1990 while he was working at the police's commercial branch.

"I was working under General Nallie Hulne in Pretoria. He is a mentor to me. He, and a person like advocate Frank Kahn SC [former attorney-general of the Western Cape] gave so much more than direction to my life."

He completed his articles at Pricewaterhouse. At the time, forensic auditing was in its youth. There were only one or two auditors who gave evidence. "There was very little prevention in the form of legislation, and very little detection. But the principle is ancient. If you mix money and people, some of them will become dishonest."

Today Van der Walt is a director of the first formal forensic unit to be formed in South Africa. "KPMG is a world leader. We are recognised worldwide for our ground-breaking work," he said.

But in the beginning of the 1990s, when he was still "in his first days" at the commercial crime unit, he received a phone call from Hulne. "Frank [Kahn] was there. He said to me: 'You've just scored yourself a weekend in Cape Town'."

That was the start of Van der Walt's investigation of stock exchange whizz kid Greg Blank.

"When I came on the case we only had suspicions. I knew nothing about shares. I sat for months studying the rules and laws of the stock exchange. And then I realised that it was a transaction like any other. And where there is a transaction, there is cash. I just followed the money."

It was during this case that Van der Walt finally realised that this was what he wanted to do.

"After I completed my national service at the commercial branch, I stayed on as a consultant to the police. I joined the Office of Serious Economic Offences (OSEO) in 1991. At the time I had a laptop, weighing 15kg, that I had to run around with at airports. You know, when I got on that plane to Cape Town it was the first time I'd been on a plane. And I never really got off again. I am the guy you see running at the airport. I know exactly what to do to get to the boarding gates very quickly."

It was at the OSEO that Van der Walt cemented the foundations of his career. "I learned so much. I met people there who are still my friends.

"When I was asked to join KPMG I was at a crossroads in my career. I either had to continue in my own name or join a big firm. I want to make a difference. I learn so much from the people I work with."

In August 1994 he joined KPMG. "On my very first day at work I received a phone call telling me I had my first case. Since then, not a day has gone by without me having work," he said. Joining KPMG opened up the corporate world to Van der Walt. "I do a bit of corporate work, some work for the state. A lot of my investigations do not end in prosecutions."

His work ranges from doing calculations in a coal mine to giving evidence in Sweden about the losses suffered by a company when the construction of a Siberian diamond mine was cancelled.

"I don't only investigate crime. It's what keeps me sane," he said.

The Shaik case, Van der Walt pointed out, was "an enormous task". After they had gone through 152 000 pages of documents, he had to write his report. "At one stage I was working 360 hours a month. When we were on deadline we decided it took too long to travel between Johannesburg and Pretoria. We just stayed in Pretoria."

At court Van der Walt was assisted by Riaan Beekman, who was his manager in the case. "I am not that much involved in formal training anymore, but I like working with people," Van der Walt said. "I don't like cloning people. I like their unique characteristics. I look at what Riaan did in this case, and I think that one day he will be so much better than me.

"A case like this is a feather in the state's cap. It shows its trust in the judicial systems."

It is to his wife of 17 years that he pays tribute for keeping everything together while he worked so hard that he sometimes forgot what day of the week it was.

"I have an amazing wife," he said. "She is an angel. We have three boys. I love them very much. My wife allows me to live my dream."

It was back to his family that Van der Walt went when he left Durban on Thursday. Beekman graduated from Rand Afrikaans University in 1998. He did his articles at KPMG. "Oh yes," he said, laughing at his mentor, " I passed the CA exam the first time.

"I will do another hundred of these cases," he said a day after the two of them completed one of the biggest jobs of their lives so far.

"When Johan phoned me about the case, he asked if I was scared. I never even thought about it. I just said 'I'm in'.

"I was always attracted by forensic work. I like the unpredictability. I like the people we work with. For me this is a case that will go down in history. It was such a lot of work. I was the project manager. Johan and I looked at the papers the Scorpions gave us and realised it would be impossible for one person to do this.

"The deadlines were sometimes frightening, but we worked seven days a week, until 2am or 3am. I have a little son aged two. My wife is also a chartered accountant, which makes it easier for her to understand. She teaches at RAU.

"Without her I would not have made it through this case. She had to learn to do a lot of things, like keeping the swimming pool blue. Now she does that better than I used to," he said. It was Beekman who had to co-ordinate the sets of files, the logistics and schedules. "I know how Johan likes his schedules," he laughed.

It was also Beekman who had to help Judge Hilary Squires and his assessors find their way around the files containing the epic report.

"I took notes while Johan gave evidence. I noted what we had to have another look at. While he was under cross-examination I stayed with him, as he was not allowed to speak to the state's team. Then I became the sounding board."

Apart from working on the Shaik case, Beekman also does training in fraud awareness.

"After what happened at Enron, there is an increasing expectation, worldwide, that auditors must be on the lookout," he said. The crooks were getting more and more clever, he added.

"We had some really hard times together," Beekman said.

"But Johan was great to work with. We made the perfect team."

With acknowledgement to The Sunday Independent.