The man who duped KwaZulu-Natal police into believing he was a Hawks brigadier was found hanged in a police holding cell in Pretoria, the Independent Police Investigative Directorate said on Monday.
"He was arrested the same day he was found dead," said Ipid spokesperson Moses Dlamini.
"An investigation is underway. I can't say if there was foul play. That will be established during the investigation."
Musa Muzi Khumalo was being held for murder and for impersonating a police officer.
He was found dead in a holding cell in the Pretoria Moot police station at 3.15pm on Saturday.
"The deceased was allegedly found hanging from his cell window when the cells were visited. He is alleged to have hanged himself with torn strips from his blanket...."
Khumalo escaped from a Johannesburg jail last year, allegedly with the help of a warder, days after being charged with a 2007 murder in Chatsworth, Durban, IOL reported earlier this year.
It was when Johannesburg police circulated his photograph that KwaZulu-Natal recognised him as a police brigadier, attached to the Durban Hawks, who had helped the police recover more than 40 stolen and hijacked cars.
At the time it was feared that he was involved in a car theft and hijacking syndicate, and that he might have used his phony position to shut down opposition crime syndicates.
KwaZulu-Natal police spokesperson Lt-Col Vincent Mdunge reportedly said Khumalo was neither on the police payroll, nor had he been issued with an appointment certificate.
According to IOL, Mdunge said Khumalo, a Zimbabwean, faked his own death in 2008, but was resurrected as a South African and obtained a South African passport and identity document.
He fled after being found out, and a team of detectives was sent to search for him in Mozambique and Zimbabwe. Crime intelligence units and tracking teams in KwaZulu-Natal and Gauteng were also placed on the lookout in case he had returned to Johannesburg.
National police commissioner General Riah Phiyega and Hawks boss Lt-Gen Anwar Dramat were said to be taking a personal interest in the case.
In a separate incident in Mpumalanga, a handcuffed man was found hanged in a holding cell at the Blinkpan police station at 3.30pm on Sunday, Dlamini said.
"The suspect was found dead with his hands handcuffed behind his back, with a noose around his neck, [hanging] from a plastic strip," Dlamini said.
Sizwe Makhathini (22) was from Mnambithi, in KwaZulu-Natal, and had been arrested for armed robbery.
"He was booked out of prison, where he was being held as an awaiting trial inmate, by members of the Middelburg organised crime unit."
He was taken to the police station during the investigation and was put into a cell alone.
Dlamini said Ipid investigators had attended the scene.
"The investigation will seek to establish how a person who is restrained with his hands cuffed to the back can hang himself."
A post-mortem would be carried out during the week.
No arrests had been made in either case.