The mystery surrounding the death of South African cricketer Tertius Bosch has deepened with a private investigator's claim that the sportsman had said he knew something was about to happen to him.

This was revealed by Hennie Els - a private investigator hired by Bosch's family to investigate irregularities at the cricketer's dentistry practice in Pinetown - during the exhumation of Bosch's body at Durban's Queensburgh cemetery on Tuesday.

Els said Bosch, who played one Test match for South Africa in 1991/92, had written three letters, one to his eldest son, Corbin, aged seven, another to his wife Karen-Ann and a third to his lawyer, Mike Nolan.

"The instructions accompanying the letters stated that they were only to be opened after his death and were written in such a way that he knew that something was wrong and that he may be in danger," said Els.

The release of the letters came hours after the launch of a police inquest into Bosch's death.

In the letter to his son, Bosch apologised for not being able to be at his 21st birthday and begged him not to believe any of the rumours which would be spread after his death.

Dr Reggie Perumal, a private forensic pathologist hired by the family to conduct the autopsy on Bosch, said it was the key to the puzzle.

"I cannot say whether Bosch died from poisoning and I will not know until the test results are back," he said after inspecting the body.

The test is being conducted to determine whether Bosch died from natural causes or from a criminal act such as poisoning.

Fuelling speculation that he was poisoned is the mysterious illness of Mrs Bosch's ex-lover, Henry Selzer.

Selzer and Karen-Ann Bosch were in a serious relationship from June last year, but decided to end it after the allegations of a possible poisoning emerged.

Selzer said he began experiencing symptoms at the end of October last year similar to those suffered by Bosch before he died.

"I suffered from partial paralysis, numbness, pins and needles, but neither my doctor, Dr Hugh Staub, a specialist neurologist, nor I had any idea what was causing the symptoms. I will be going to Perumal today, who will be conducting several tests on me to try to find out what is wrong with me."

Commenting on his relationship with Mrs Bosch, Selzer said he had put things on ice because of the allegations. "I want hard facts and I want people to substantiate them before I can re-evaluate our relationship. Knowing her, I am shocked at the allegations and find it hard to believe them," he said.

Perumal refused to disclose what type of tests would be conducted on Selzer, but said he was hoping they would reveal the answers everyone was looking for.

Bosch was suffering from Guillian-Barre Syndrome when he died at Westville Hospital on Valentine's Day last year, aged 33. Only about five percent of those suffering from the illness die.

Bosch's family were never happy with the circumstances of his death and are hoping the exhumation will answer their questions.

In addition to his wife and son Corbin, Bosch is survived by another son, Eaton, aged three.

Els said that he had been investigating the irregularities at Bosch's practice on behalf of the family for the past eight months.

"I was asked to find out what was behind the three letters," he said. In the letter addressed to his wife, Bosch said he knew about "her affairs" and "blamed her for killing his love for her".

The letter to Nolan stated that his eldest son Corbin was to be the sole beneficiary of his estate, while the last letter was the apology to Corbin. "From the letters it is clear that Bosch knew that something was not right, but whether he knew that he was going to die is another matter," Els said.

Perumal said he was looking for a specific poison group, which could have been administered to Bosch over a period of time. "We will conduct other chemical tests to see if we can find anything else which could be linked to Bosch's death."