Former head of the Independent Police Investigative Directorate (IPID), Robert McBride told the Zondo Commission that former police minister Nkosinathi Nhleko must explain his appointment of a convicted criminal as his chief of staff.
"Why would a minister of police hire a convicted criminal who is not South African and is still flashing his illegal documents?
"There is no reasonable explanation as to why the minister would insist on employing this particular person there," McBride told the Commission of Inquiry into State Capture on Tuesday.
The former IPID head was referring to a Leon Mbangwa whose real name is Lionel Moyo.
The man in question is allegedly a Zimbabwean citizen who was arrested for a false identification document in 2000.
Mbangwa was found guilty of fraud and jailed for four years on December 13, 2002, police spokesperson Sergeant Ann Poortman confirmed to News24 in an earlier report.
McBride later learned that Mbangwa did not have the security clearance to be hired in a political post.
Nhleko at the time requested clearance for Mbangwa through IPID, instead of the South African Police Service (SAPS).
"The state security agency wrote a report to IPID and indicated that he has a conviction and it relates to dishonesty and he has financial problems. They did not pick up that he was a Zimbabwean and that he had not been naturalised.
"It is an intelligence failure and a security risk. How does an acting police commissioner feel safe to send documents when the chief of staff deals with it?" McBride said.
Mbangwa also recently appeared in court on March 31 for having false documentation and qualifications, McBride added.
"The [former] minister must explain this. He has never sought to explain it," the former IPID boss concluded.
McBride has completed his evidence to the Zondo Commission.
The inquiry continues on Wednesday with the testimony of former KwaZulu-Natal Hawks head, Johan Booysen.