Johannesburg - Zimbabwean first lady Grace Mugabe has not handed herself over to police after she allegedly assaulted a 20-year-old model with an extension cord in Sandton at the weekend."[She] is not under arrest because she co-operated, and handed herself over to police," Police Minister Fikile Mbalula told eNCA earlier on Tuesday. She was expected to appear in court later on Tuesday. "The negotiations over the suspect handing herself over have not concluded and our investigations have not finalised," police national spokesman Vishnu Naidoo told AFP later.Her whereabouts were unknown to police.Without naming Mugabe, national police confirmed that a case of with intent to do grievous bodily harm was opened against a "prominent woman" after the alleged assault at a hotel in Sandton. "The investigation into this case has already reached an advanced stage. The suspect in this matter cannot be named because she has not as yet appeared in court. We request that the SAPS be allowed to conduct a thorough investigation and to follow due process," Brigadier Vishnu Naidoo said in a statement. The Zimbabwean Mail reported that Mugabe was in the country to have her foot examined following an accident at the Harare international airport. The article was updated after new information was received from the SAPS.