Zindzi Mandela, the daughter of South African human rights icons Nelson and Winnie Mandela, who also served as the nation’s ambassador to Denmark died Sunday in Johannesburg, according to South African broadcast network SABC and the Nelson Mandela Foundation. 

She was 59. A cause of death has not yet been released

“Zindzi will be remembered for a rich and extraordinary life, marked by many iconic moments. The years she spent banished with Mama Winnie Madikizela-Mandela to the small town of Brandfort,” the Foundation said in a statement. “That summer’s day in February 1985 at Jabulani Stadium when she read to the world Madiba’s rejection of President Botha’s offer of a conditional release from prison. Her own courageous work in underground structures. Public service as South African Ambassador to Denmark.

“We join with many in saying hamba kakuhle [“Go Well”] to an outstanding South African.”

Zindziswa Mandela was the youngest of Winnie and Nelson Mandela’s two daughters and has four half-siblings by her father. She was 18 months old when her father was first sent to prison by the South African government. Eventually he was sentenced to life imprisonment in 1964. She was often cared for by her older sister Zenani during the periods in which her mother was also imprisoned.

When Winnie Mandela was banished by the apartheid government to South Africa’s Orange Free State in 1977, Zindzi went there to live with her. Her own human rights career began to grow in 1985 when then-president P.W. Botha offered her father a conditional release in 1985. 

But he refused, and Zindzi read his communication, publicly balking at the offer: ″I cannot sell my birthright, nor am I prepared to sell the birthright of the people, to be free,″ Mandela said through his daughter. It was his first public statement since being sentenced to life at Robben Island.

Zindzi said that prison authorities had tried to stop the statement from getting out, but her father insisted that it did. “...He would have none of this and made it clear that he would make the statement to you, the people,″ she said at the time.

She went on to serve as deputy president of the Soweto Youth Congress, according to a biography, and was a part of the Release Mandela Campaign. She helped to launch a branch of the African National Congress with Walter Sisulu in South Africa’s Gauteng Province.

In 2014, she was appointed South Africa’s ambassador to Denmark and was serving in that position at the time of her death.

She has been married twice and has four children.

Current South African President Cyril Ramaphosa, remarking on Mandela’s life said he was “deeply saddened” by news of her death.

“Zindzi Mandela was a household name nationally and internationally, who during our years of struggle brought home the inhumanity of the apartheid system and the unshakeable resolve of our fight for freedom,” he said.