Zindzi Mandela died on anniversary of death of Madiba's eldest son Thembekile

July 13 is already a painful day for the family of the late former president Nelson Mandela.

As the Mandela family mourned the passing of Zindziswa Mandela on Monday, the Nelson Mandela Foundation revealed that it was also on this day that Nelson Mandela's son  Thembekile died back in 1969.

Thembekile was 24 years old when he died in a car accident in Cape Town. He was the father of two daughters, Ndileka and Nandi. 

Mandela had already been imprisoned on Robben Island when Thembi died and was denied permission to attend the funeral. 

Thembekile's mother was Mandela’s first wife, Evelyn Mase.

Together the couple had four children: Thembekile; Makaziwe, who died in infancy; a son, Makgatho; and another daughter, who they also named Makaziwe in remembrance of their deceased daughter. 

Zindzi was one of two children that former president Nelson Mandela had with his second wife, struggle stalwart Winnie Madikizela-Mandela. Their other daughter is Zenani. 

Zindzi died in Johannesburg on Monday. She was 59.

The cause of her death was not revealed.