Cape Town – Investigations into the alleged assault of a 20-year-old by Zimbabwean first lady Grace Mugabe have been halted, a police spokesperson said on Friday. “Our investigation is completed, but we received a note verbale which indicates that the suspect in the case applied for diplomatic immunity,” police spokesperson Vish Naidoo told Netwerk24. A note verbale is a piece of diplomatic correspondence, which is less formal than a diplomatic note.“In light of this, it was decided to provisionally halt investigations.”Mugabe allegedly assaulted Gabriella Engels in a Sandton Hotel on Sunday. Engels had been visiting Mugabe's two sons. On Wednesday, the ministry of police said Mugabe was still in the country but invoked diplomatic immunity. Read more: 'Impossible' for Grace Mugabe to have a diplomatic passport - expertAccording to South African legislation, diplomatic immunity can only be invoked if an official’s entry into South Africa was gazetted before their arrival. The Department of International Relations and Co-operation (Dirco) did respond to a News24 enquiry whether Mugabe’s visit was gazetted. Mugabe was in SA to receive medical care for an injured foot, the Zimbabwe Mail previously reported.On Thursday, Police Minister Fikile Mbalula said police put out a "red alert" at South African borders for Mugabe, in case she attempted to leave the country.Read more: 'Red alert' for Grace Mugabe at SA bordersMugabe is expected to attend a Southern African Development Community (SADC) meeting underway in Pretoria, as well as attend to "personal matters,” the Police ministry previously said. Mugabe’s spokesperson George Charamba has not responded to repeated requests for comment.