Police are now investigating the death of Wiandre Pretorius, 41, who last week said he had survived an assassination attempt.

Pretorius's name had been mentioned at the ongoing corruption inquiry, known as the Madlanga Commission. This was in connection with the 2022 murder of a man, Emmanuel Mbense, allegedly at the hands of police officers.

Four of the 12 people named as persons of interest in that killing are now dead themselves, a police spokesperson said.

At 22:00 local time (20:00 GMT) on Saturday the police received reports that a man had taken his own life at a petrol station in Brakpan, east of Johannesburg. At the scene, officers found Pretorius's body with a firearm next to it, spokesperson Brig Athlenda Mathe said.

The police are now looking at CCTV footage to confirm what happened. There had been reports that Pretorius had been involved in a row with his fiancée at the petrol station before taking his own life.

The murder four years ago of Mbense is one of several issues that has come up at the Madlanga Commission, which was set up by President Cyril Ramaphosa after a senior police officer alleged that organised crime groups had infiltrated the government.

At a hearing last year, a man, only identified at the time as Witness D, said that in 2022 he had been ordered to get rid of the body of someone accused of robbery who had allegedly been tortured and killed by police officers.

Witness D also alleged that Pretorius, who was not a policeman but had previously served as a police reservist, was involved.

The witness, later named as Marius van der Merwe, was shot death three weeks after testifying.

Police spokesperson Mathe said on Sunday that Pretorius had been questioned and his firearms confiscated in connection with Van der Merwe's killing.

Mathe added that the death of Pretorius on Saturday night leaves only eight of the original 12 persons of interest in the killing of Mbense still alive.

Three were killed "execution style" – one in 2023 and two last year.

"The question is: are we dealing with a syndicate that is eliminating each other in relation to the Emmanel Mbense murder? That is what our detectives are probing," Mathe told reporters.

Last week, police began investigating whether Pretorius himself had been the target of an assassination attempt after he said that his vehicle had been shot at.

In connection with the murder of Mbense, Mathe said that "arrests are imminent" following an investigation by the independent police watchdog body.

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