While those serving on the parliamentary inquiry into state capture sift thousands of pages of evidence and assess hundreds of hours of testimony to determine whose hands are dirty, one line of investigation being pursued by DA MP Natasha Mazzone may provide a breakthrough.
During her questioning on Tuesday of Eskom head of generation Matshela Koko, Mazzone told him she had made applications in terms of the Promotion of Access to Information Act (PAIA) to both comb Home Affairs records and to "forensically audit" a certain email.
The email was purportedly sent from Koko's personal email address. It is just one of the between 100,000 and 200,000 explosive emails that came to light last year in the wake of the so-called Gupta leaks.
Mazzone asked Koko if his personal email address was matshele2010@yahoo.com. He told her it was, but that this particular address had been "discontinued by Yahoo".
The reason was "illegal or unauthorised" activity.
"It later became active, and then became discontinued again," he told her.
Mazzone advised him that a few "interesting and disturbing things" had happened when it was active.
"On the fourth of November 2015... an email left [your] address and went to the DG (director-general) of public enterprises, who had a private email address.
"And it said: 'Please give to the boss. The fight begins'. And that email was then forwarded to wdrsa@gmail.com, and [to] Ashu Chawla. We know Ashu Chawla is from Sahara Computers, but this 'wdrsa', who was that?
"We've now found out that it's actually Rajesh Gupta, otherwise known as 'Tony' Gupta. That concerns me tremendously. Because who are we calling the boss, and what fight is on?"
Koko responded: "I have never sent an email to DG Seleke."
Mazzone asked him if he thought this email, and others, were "created" to put him in a bad light.
Koko replied: "I'm saying I've heard many versions about those emails, and I think there's a way to verify them, and they must be verified."
Mazzone assured him this was happening.
"I've [made a PAIA application] for these documents to be forensically audited. Because I think we need to know for sure that these are legitimate email addresses, and as the public enterprises committee, we certainly do need to know that."
Parliament's public enterprises portfolio committee is conducting the probe into state capture.
Mazzone said other emails revealed Koko was in Dubai in 2015. Further, it was alleged that Mineral Resources Minister Mosebenzi Zwane joined the Guptas in Switzerland for the sale of Glencore's Optimum mine to Tegeta.
"Other Gupta allies, in the meantime, were in Dubai at the time, at the Guptas' expense, including Mr Matshela Koko and Mr [Anoj] Singh," she said.
Koko insisted he was not in Dubai in 2015.
Mazzone told him she was checking this with Home Affairs.
"So when I [using the PAIA] get the documents from Home Affairs as to who entered or exited the country..."
At this point, Koko interrupted her: "I will give you my passport. You don't need to go to Home Affairs."
"No, I'm going to go to Home Affairs because passports are easily duplicated. I need to know from Home Affairs," she said.
Koko then repeated: "I was not in Dubai in 2015. I confirmed I was in Dubai in January 2016.
Earlier on Tuesday, Koko denied that the visit he made to Dubai in January 2016 was paid for by the Guptas.
He told the inquiry -- in response to a question from evidence leader Ntuthuzelo Vanara that the trip was, in fact, part of a family holiday, which he had paid for himself.
"On December 23 [2015]... my family and myself went to Bali. We flew through Doha. When we returned [in January], three of my daughters came back through Doha. My wife and I and my son came via Dubai. I'm happy to present the passports for the six members of my family."
On the expenses, Koko said he paid the bills.
"I did direct payments myself. If you bother to contact the hotel, you'll establish such."
Vanara then asked: "And you confirm Sahara Computers did not pay? You confirm you paid?"
Koko told him: "Sahara Computers did not pay for my travels at all."
Taking this further on Tuesday evening, Mazzone said his [Koko's] response to Vanara's questions had concerned her.
"Was this like the most unbelievable coincidence? Why would Mr Chawla be booking your hotel for you?"
"This concerns me because it's on the Gupta-linked emails... The account for your stay and details for your stay have been made public. And what it does show is that [Sahara Computers CEO] Mr Ashu Chawla was also in Dubai for that one day with you. He was staying in the hotel with you.
"And the email actually shows your bookings were done together, and they were done through [the Gupta-linked company] Sahara Computers, and your [hotel] reservation number was 467415. Now I don't understand. Was this like the most unbelievable coincidence? Why would Mr Chawla be booking your hotel for you?"
Mazzone said the email went so far as to give a detailed breakdown of the invoice, which actually showed Koko had a guest with him at an additional cost of Dirham 275 (about R890) above the room price.
"I have no doubt your wife was there because it shows an extra person with you. But why was your booking done through Sahara?"
Koko told her he did not meet Chawla in Dubai.
"He did not book for me. We did the bookings. If you have a chance, and I think it's easily done, contact the hotel."
Mazzone told him she had the email from the hotel.
"That's one of the things, the reservation... is on the Oberoi Hotel letterhead. You see the point, Mr Koko, I even have the name of the chauffeur who fetched you from the airport and brought you to the hotel," she said.
"I would like to see that. I don't know what you're talking about," Koko replied.
The replies received by Mazzone to the questions she posed on Tuesday evening suggest one of two things. Either some or all of the leaked email are wrong, fakes designed to cause maximum reputational damage; or, something is very wrong with some or all of Koko's testimony, delivered under oath and broadcast live from Parliament.