The move has been delayed until after this weekend's conference by the ruling African National Conference. Winnie Mandela is an ANC MP.
Lolo Sono and Sibuniso Tshabalala were last seen – seeming to have been severely beaten – with Mrs Mandela in her Soweto home in November 1988. Until September this year, South African authorities have denied any knowledge of their whereabouts.
The police have now confirmed they know where their bodies are buried and South Africa's National Prosecuting Authority (NPA) has told their families they will exhume their bodies in January. Family members have been DNA-tested to aid identification and for a forensic autopsy to establish new evidence.
"Because the ANC are still busy with this Mangaung thing [the ANC's electoral conference], they said we must wait until January next year," Lolo Sono's mother, Dorothy, told the Sunday Herald in an exclusive interview on Friday.
Sibuniso Tshabalala's mother, Nomsa, publicly accused Mrs Mandela of abducting and murdering her son and Lolo Sono when she testified before Archbishop Desmond Tutu at the Truth and Reconciliation Commission (TRC) in 1977. She stated under oath: "She [Mrs Mandela] is the one who committed this atrocity - Yes, she did kill them, just like Stompie.
Winnie Mandela was convicted in 1991 of kidnapping and being an accessory to the assault of Stompie Moeketsi, 14, which led to his death. Her six-year jail sentence was reduced to a fine and a two-year suspended sentence on appeal.
"I'm scared of Winnie," Nomsa Tshabalala told the TRC. "There's quite a number of things that she has done.
"I would request Winnie to give Sibuniso back to me. I want Sibuniso or his bones and remains. She knows, deep inside of her, she knows [what happened to Sibuniso and Lolo] - I'd like to find out as to where my son has been buried."
No action was taken against Mrs Mandela on those accusations and a docket compiled by police on the case went missing, as have several dockets linked to assaults by the Mandela United Football Club, Mrs Mandela's private bodyguard.
The new revelations concerning the missing bodies of Sono and Tshabalala – a case which has been a cause célèbre in South Africa as major as any big murder or missing persons mystery in Europe or North America – came at the end of my research for a book on the consequences of the Stompie Moeketsi affair and other Mandela United Football Club actions.
I have kept close contact with Caroline Sono, Lolo Sono's stepmother, over the years. With her late husband, Nicodemus, she campaigned unsuccessfully for more than two decades for Mrs Mandela – known as Madikizela-Mandela since Nelson Mandela divorced her in 1996 – to reveal the burial site of her stepson and return his bones so his soul can be laid to rest according to African tradition. "If he is not buried [properly], his spirit is roaming around," she told me.
On my latest visit to her in Soweto, she told me of the NPA's discovery and its exhumation plan. But she said the NPA had cautioned all the parents to say nothing publicly, for reasons that are unclear.
Caroline Sono took my hand and wept as she said: "I hoped for so many years that my son was still alive in some foreign country. Now I know he is dead. What we want is our minds put at rest.
"We know justice is never done for people like us in South Africa, but in our society we have to bury our loved ones properly for there to be closure. We just want Lolo's bones so that we can bury him properly and his spirit can be with us, and for Winnie to say she's sorry. She's not the Mother of the Nation [as Mrs Mandela was once known], she's the killer of the nation."
Caroline, a priest at St James Apostolic Church in Soweto, said both biological mothers had been DNA-sampled by NPA officials, plus their sons and daughters. Nomsa Tshabalala, whom I have interviewed several times in the past, was now "too frightened" to speak, said Caroline. I tried to arrange a meeting with Nomsa in a Soweto restaurant through an intermediary, but she did not turn up. After a long search, I finally traced Dorothy Sono on Friday and spoke to her.
Caroline Sono condemned the apparent attempt by the NPA to silence Nomsa Tshabalala and Dorothy Sono and to avoid embarrassing the ANC in advance of its conference. She said: "Mrs Mandela should not be above the law - There seems to be no justice in this world, because once the TRC was over [in December 1997] and we had given our evidence, nobody in power contacted us. Winnie seems untouchable."
Lolo Sono and Sibuniso Tshabalala disappeared on the evening of November 13, 1988 – seven weeks before the murder of Stompie Moeketsi – after a series of strange events.
On November 9, a police SWAT team attacked the Soweto house of Jerry Vusi Richardson, the so-called "chief coach" of Mrs Mandela's "football team". In reality, Richardson was the violent lieutenant in charge of her bodyguard.
Lolo and Sibuniso – who had both expressed a desire to go into exile and become guerrillas with Umkhonto we Sizwe ("The Spear of the Nation"), the military wing of the then-banned and exiled ANC – had been taken by Mrs Mandela's driver to Richardson's house before the attack, but had been told to go away.
Soon after they left Richardson's house, the police SWAT assault began and Lolo and Sibuniso and Richardson's neighbours watched. The youths told their parents what had happened. Three days later, Lolo failed to return to his home.
On the evening of November 13, Mrs Mandela turned up in her familiar blue minibus combi at the home of Nicodemus and Caroline Sono. Lolo Sono, his face swollen, was among the passengers, as were several Football Club members.
Nicodemus Sono was shocked to see his son being held with a gun to his head by a big man who gripped Lolo by his collar. Mrs Mandela demanded that Nicodemus hand over certain documents and photos belonging to Lolo. Nicodemus said there were only photos among the boy's possessions, no documents.
He said: "She told me she was taking Lolo away because he was a spy and that two comrades had been killed because of him. I saw Lolo had been badly beaten. He was shaking and his eyes were swollen. I pleaded with her that she'd got it wrong and that Lolo was an [ANC] activist." When Lolo tried to speak, he was told to shut up by Mrs Mandela.
Because his son was trembling, he asked Mrs Mandela to permit Caroline Sono to fetch a sweater for Lolo. As he handed the sweater to his son, Nicodemus managed to have a quick word with him: "He said he had gone to Winnie's [house] of his own free will because he wanted to be smuggled out of the country to train for the struggle.
"Instead, he had been beaten up. I pleaded with Winnie to return my son. She totally refused. She said, 'I am taking this dog away. The movement will see what to do with him.' I assumed she meant she would send him across the border to the ANC camps. It never crossed my mind that he was going to be killed, because Winnie and I had done so many things together in the past. I was seeing another side of Winnie altogether."
Nicodemus Sono, who died a few months ago from a diabetic illness, never saw his son again.
Sibuniso Tshabalala was last seen by his mother the following day when he told her he was going to Winnie Mandela's house to find out what had happened to Lolo. Nomsa Tshabalala later received a phone call from Sibuniso, who was only able to tell her he was with Lolo before the phone went dead. She never heard from him again.
Evidence given to the TRC by two Football Club members who had been in Mrs Mandela's minibus combi that night – the driver Michael Siyakamela and a young Zulu named Katiza Cebekhulu – mirrored the account of Nicodemus Sono.
Cebekhulu also said that when the minibus combi returned to Mrs Mandela's house she ordered Lolo Sono to be killed. "Winnie said, 'Take him away' – It was her order to kill."
Cebekhulu said Lolo was taken into Mrs Mandela's garage and he never saw him again.
Cebekhulu also testified at the TRC that the following month he saw Mrs Mandela stabbing Stompie Moeketsi next to the jacuzzi behind her house.
Although Siyakamela gave statements to TRC investigators, the state attorney-general, the police and a foreign correspondent, he failed to appear at the TRC. He telephoned a TRC investigator and said he had been contacted by Mrs Mandela and did not want to testify because he was frightened. His subsequent fate or whereabouts is unknown.
Richardson later made a statement saying he had killed Sono and that Tshabalala had been killed by two other Football Club members, Guybon Khubeka, one of the club's chief enforcers, and another unidentified member known as Ninja.
Applying for amnesty under TRC rules for a number of killings and assaults, Richardson said Sono and Tshabalala were kept for several days at Mrs Mandela's home, their hands and feet bound. Richardson testified that it was agreed the "youths should be dumped". This decision "came from Sonwabo [a senior Football Club member], and Mommy was a participant because she was the one who gave the go-ahead or the green light for anything to happen".
Richardson, who expressed a childlike devotion to Mrs Mandela, frequently referred to her as "Mommy". He was not granted amnesty and died in prison in 2009 at the age of 59.
Mrs Mandela was not charged or even interviewed in connection with the disappearances of Lolo Sono and Sibuniso Tshabalala, though the TRC later concluded there was a prima facie case against her.
Among the many unsolved mysteries is that Richardson was proven at the TRC hearings to be a police informer and that, though he claimed to have murdered Lolo Sono on behalf of "Mommy", he was in fact in police detention when the youths disappeared.
In its final report, the TRC concluded that the two youths were last seen alive at Mrs Mandela's home, that she was involved in their abduction and "therefore, that Madikizela-Mandela must accept responsibility for the disappearance of Lolo Sono and Sibuniso Tshabalala".
Piers Pigou, a senior member of the TRC's Investigation Unit who cross-examined Mrs Mandela, said: "It remains to be seen whether a criminal investigation is pursued in this matter. But on past experience, it seems unlikely as hundreds if not thousands of other apartheid-era cases, many of which are high profile, have effectively been abandoned by the authorities, undermining the promise that there would be action in the post-TRC era."
When the Sunday Herald asked NPA spokeswoman Bulelwa Makeke exactly when the bodies of Lolo Sono and Sibuniso Tshabalala would be exhumed, she referred the issue to her media assistant, Makhosini Nkosi. He asked for questions to be emailed to him for reference to senior NPA officials.
The Sunday Herald submitted four questions, including one asking what kind of criminal investigation will be now launched. At the time of going to press, the NPA had not replied.
THE CONVICTED MURDERER
'Winnie Mandela was as responsible for this crime as I was, but in South Africa if you are a big person the law protects you'
WINNIE Mandela has been accused of being behind the murder of her doctor by one of the two men convicted of the killing.
In an exclusive interview with the Sunday Herald, Thulani Dlamini insisted Mrs Mandela was implicated in the murder of Dr Abu-Baker Asvat.
The doctor examined Stompie Moeketsi while he was being beaten to death at her home, and, it is claimed, warned her the boy might die.
"She [Mrs Mandela] never visited us [in prison]," said Dlamini, recently freed from jail. "I was angry because she also was responsible for the crime. She was as responsible as I was. But in South Africa if you are a big person the law protects you."
The other Zulu convicted of the murder, Zakhele Mbatha, testified to the Truth and Reconciliation Committee in 1997 and blamed Mrs Mandela for the murder.
He said: "All I have done I did because I was tempted by a very clever person, older than me - I killed Dr Asvat by shooting him. This was under instructions from Mrs Mandela and I genuinely believed that I would be benefiting the future political system."
According to allegations made at the TRC, Mrs Mandela hired the two illiterate, jobless Zulu youths for 20,000 rand [then nearly £600] each to assassinate her doctor in his Soweto surgery with a 9mm pistol she was alleged to have provided.
Dr Asvat died in the arms of his surgery nurse, the late Albertina Sisulu, wife of Nelson Mandela's closest friend on Robben Island, Walter Sisulu. One TRC document quotes Mrs Sisulu as saying of Dr Asvat's murder: "It was Winnie."
Dlamini and Mbatha were arrested and sentenced to death, commuted to 25 years life imprisonment. Mrs Mandela was neither questioned nor charged over her doctor's death.
Mbatha told the TRC police tortured him and gave him a ready-made confession to sign which omitted Winnie Mandela's role. Mbatha killed himself after he and Dlamini were paroled.
After the assassination, I interviewed Dr Asvat's closest friend, Johannesburg businessman Reggie Jana, who said the doctor visited him shortly after he had examined Stompie Moeketsi's wounds and had warned Mrs Mandela the boy might die.
According to Jana, Dr Asvat said he had been told by Mrs Mandela to say nothing about what he had seen. "The man had fear in him," said Jana, adding that Asvat said: "This effing bitch is giving me grief, causing problems, and I fear for my life."
I found Thulani Dlamini on my recent trip in Soweto, the township of two million people near Johannesburg, where he has been living since being paroled.
It was a long and difficult search. I had been tipped off that Dlamini had been paroled and that the South African media had inexplicably not tried to find him. I wanted to talk to him because my new book on Winnie Mandela is less about her and her vigilantes than about the myriad small people affected by the Football Club killings and other violence.
Fifteen years earlier I watched Dlamini appear in prison chains and cuffs before the TRC in December 1997. The TRC said Dlamini had made at least three police statements over eight years implicating Mrs Mandela in the murder of Dr Asvat. But it said Dlamini's statements were never put before a court "and it remains unclear why no investigations were conducted regarding his allegations".
Dlamini testified that he was taken to Mrs Mandela's house by an intermediary where she offered him and Mbatha 20,000 rand to kill her doctor. The intermediary handed them a gun from Mrs Mandela and briefed them on the mission. Mrs Mandela called them back for a second time to make sure they understood their instructions.
"When we arrived there inside the house, she said she hoped that we understand exactly what we have to do," said Dlamini.
Mrs Mandela sent a Football Club member to guide them to Dr Asvat's surgery. Mbatha shot the doctor dead. The youths fled but were arrested days later.