The list of experienced South African Revenue Service (Sars) employees who are leaving the institution appears to be continuing unabated, with the latest resignation coming from a senior manager in the criminal investigations of the tax and customs enforcement unit.

News24 has learnt that Ronel van Wyk resigned this month and is working the rest of her notice period at home. Van Wyk was allegedly escorted off the premises on the day she resigned.

According to LinkedIn, Van Wyk has worked at Sars for 25 years. She has been a senior manager for 16 of those years.

She has a BA in Police Science, Political science and government from Unisa, an MBA from the University of Pretoria and has completed the Sars Women in Leadership programme at the Henley Business School.

Sars insiders have told News24 that Van Wyk was being investigated by what has come to be known as the "Mundie unit" when she resigned. This refers to an internal anti-corruption unit run by controversial figure Yegan Mundie.

It was Mundie’s unit which was involved with the investigation against Kumaran Moodley, Sars' most experienced customs investigator, and Yousuf Denath - a senior manager in the anti-corruption and security section - which saw them both suspended.

Sars has previously denied any wrongdoing by the unit.

Victim of spying

The insiders say Van Wyk "was another victim" of this unit, and that the allegations against her are slim, and are related to money her husband had put into her account.

Van Wyk would not comment on her resignation and Sars had not responded to News24's queries.

She was previously held in high regard at Sars and recently went to Paris to represent the organisation. She also presented awards at their annual Amakhwezi Award ceremony.

Van Wyk was a renowned investigator, News24 had been told, and was not swayed even though she was one of the victims of spying by dirty tobacco companies which was revealed in the @espionageafrica leaks last year.

Part of the leaks is an affidavit by Daniel Francois van der Westhuizen, who was an employee of British American Tobacco security contractor Forensic Security Services (FSS).

Attached to the affidavit is a surveillance and source report on Van Wyk which falsely claimed her husband was a Sars official. There were also photos of their home, children and cars.

Van Wyk’s resignation comes shortly after investigative journalist Jacques Pauw, who wrote the explosive bestseller The President’s Keepers, said Sars had almost no investigative capacity left at the institution.

Speaking last week at the Global Investigative Journalism Conference at Wits University, Pauw said Sars' investigative capacity had been so hollowed out after the "rogue unit" purge that it was one of the only major tax bodies in the world that did not have in-depth investigative capacity.

Long list of people who have left Sars

Van Wyk joins a long list of executives and senior employees who have left Sars in the past years.

The Huffington Post reported in December last year that almost the entire senior management team had left Sars since Tom Moyane was appointed as commissioner in September 2014, "ranging from deputy commissioner Ivan Pillay, chief operating officer Barry Hore, chief enforcement officer Gene Ravele, as well as a host of group executives, executives and senior managers".

Among some of the employees that have left the institution are: Vusi Ngqulana - the group executive for debt collection; Kosie Louw - the longest serving member of Sars executive and an internationally renowned tax-expert; Matsobane Matlwa - the chief financial officer; Elle-Sarah Rossato - she was in charge of a specialised legal and debt management team within the enforcement unit; and top investigator Asham Khan.

In February Moyane said that the outflow of experienced officials at Sars was a myth.

Just days later senior audit manager Lorraine van Esch resigned. She had been the audit manager responsible for some of the biggest, high profile tax cases in the last few years involving assessments in excess of R3-billion.

Former Sars spokesperson Adrian Lackay, at his CCMA hearing, said that between September 2014 and March 2015, 55 senior managers had left Sars.

The figure would be far higher by now.