Paralympian Oscar Pistorius is expected to appear in the Pretoria Magistrate's Court on Friday.
"He will be kept in police custody," said National Prosecuting Authority official Medupe Simasiku. Bail will be opposed when Pistorius appears, police spokesperson Brigadier Denise Beukes told reporters earlier.
She declined to elaborate.
Pistorius's model girlfriend Reeva Steenkamp was shot dead in his Pretoria home in the early hours of Thursday.
Pistorius was held at the Boschkop police station in the morning, then seen by a Sapa reporter at the Mamelodi Day Clinic after a high speed convoy drove him there.
His sister Aimee was seen arriving with a jacket and white trousers, presumed to be for his court appearance.
His lawyer Kenny Oldwage was expected to apply for bail on his behalf.
Speaking generally, and without commenting specifically on Pistorius, Beukes said it was a routine process for a suspect to be taken for a medical examination in such cases.
"The person is taken for a medical examination. It is a standard procedure," she said.
"They [hospital staff] test under the nails, they look for scratches, bruises, and blood is taken for alcohol and drug screening." Pistorius was co-operating with police.
Beukes said there had been incidents of domestic violence at his house.
"I confirm there had been previous incidents of a domestic nature at his place, but this will form part of the investigation," she said.
There was no sign of forced entry into Pistorius's house and reports that Steenkamp was shot after she was mistaken for an intruder did not emanate from police.
"As the South African Police Service, we do not have a report based on those allegations. We only heard over the radio that the woman was shot after she was mistaken for an intruder."
Beukes added later: "The surprise was that the information was given to the media. The police did not provide the information."
Beukes said forensic detectives were collecting evidence from the crime scene and journalists would not be allowed inside until police handed over the scene to the estate's security company.
Meanhile, M-Net withdrew its advertising campaign featuring Pistorius on Thursday, the television channel said.
"M-Net concluded a once-off, short-term contract with Oscar Pistorius for a six-week campaign to promote the Academy Awards," spokesperson Lani Lombard said.
"The agreement has come to an end."
Sponsors the Mail & Guardian contacted all declined to comment. One, a British telecommunications company BT spokesperson said: “We are shocked by this terrible, tragic news. We have no further comment at this stage."
Jody Hyam, communications executive for sponsor Clarins Group South Africa, which Thierry Mugler falls under, also declined to comment.
Nike South Africa told Business Day Live it will not yet withdraw its support for Paralympic icon Oscar Pistorius, alleged to have shot dead his girlfriend.
"This is a very unfortunate story and it is still under investigation. We’ll not make any decision until we hear from Oscar or his agent," Nike South Africa spokesperson Seruscka Naidoo said. – Sapa, M&G Reporter