The State pathologist, who examined Susan Rohde's body following her death in July 2016, on Thursday afternoon admitted under cross-examination that he made a mistake in calculating her time of death.
Susan's husband Jason Rohde is standing trial in the Western Cape High court for her alleged murder.
Under cross-examination by defence attorney Graham van der Spuy, a nervous Dr Akmal Coetzee-Khan said he used the cooling of body temperature to estimate that Susan passed away at 05:40 on July 24, 2016, with 95 percent accuracy.
Using this technique, Coetzee-Khan calculated that Susan passed away somewhere between 02:00 and 08:00 that day, and used the mean time as her time of death.
READ: Susan Rohde's bruise was from a handstand fall - defence
Van der Spuy said Coetzee-Khan's statement that his calculated time of death is 95 percent accurate was a lie.
He read aloud passages of research which called the mean time for the time of death the "Achilles heel" of forensic pathology.
Coetzee-Khan agreed and said he "made mistakes in the interpretation of her time of death".
"I should've provided the whole range from 02:00 until 08:00, and not provided the mean time."
Van der Spuy used this admission to cast doubt over Coetzee-Khan's entire testimony.
"The problem that we now have is what do we rely on in your evidence if you can be flawed in this major issue?"
READ: Rohde trial: Evidence may have been 'contaminated' - defence
Van der Spuy said Coetzee-Khan made several other mistakes, such as failing to take note of the room temperature, Susan's body mass index or whether a window had direct sunlight.
Earlier on Thursday, the court heard that Jason had no injuries of "significance" after his wife was found dead. Van der Spuy said that if Jason had strangled Susan, there would have been 'fight back' injuries.
In Coetzee-Khan's original forensic report, he stated that Jason claimed he had an argument with his wife before she locked herself in a bathroom on the Spier wine estate.
Jason apparently called maintenance to open the door. Once it had been opened, Susan's body was found.
She had hung herself with the cord of an electric curling iron, from a hook, at the back of the bathroom door.
Coetzee-Khan, however, determined that Susan had died from a lack of oxygen, following manual strangulation and smothering.
The State alleges that Jason murdered her and defeated/obstructed the ends of justice by "staging" her suicide and providing false information to police.
He has pleaded not guilty.
Judge Gayaat Salie-Hlophe postponed the matter to Tuesday morning.