South Africa's police directorate of complaints has opened 34 murder dockets in the police killings of 34 striking mine workers and also is investigating complaints that more than 150 arrested miners have been beaten in police custody, the directorate spokesman says.
The news came as President Jacob Zuma was grilled by the African National Congress (ANC) national executive committee over the police shootings that wounded another 78 strikers at the Lonmin platinum mine on August 16.
The killings - the worst display of state violence since apartheid ended in 1994 - have shocked the nation and damaged the reputation of Mr Zuma and his governing ANC, already fractured over Mr Zuma's bid for re-election as party president in December.
As party president, he would be guaranteed a second term as president of South Africa.
Mr Zuma's enemies claim the police shootings highlight what they say is the party's disregard for the poor.
The ANC has been unable to stem massive unemployment. Many in South Africa have inadequate housing, lack electricity and access to adequate education and health services.
Spokesman Moses Dlamini said the Independent Police Complaints Directorate has opened dockets investigating 34 murders and 32 attempted murders in the police shootings.
Mr Zuma is reported to have given the order for police to end an illegal and violent strike that began August 10 and had killed 10 people before the shootings, including two police officers hacked to death by strikers who also burned alive two mine security guards.
Police Commissioner Riah Phiyega has faced criticism for telling her officers that they "did nothing wrong".
She has said she gave the order to use live ammunition, arguing the police acted in self-defence after they were shot at.