Cape Town - It is impossible for Zimbabwean first lady Grace Mugabe to invoke diplomatic immunity if a diplomatic passport was not gazetted in advance of her trip, an international law specialist has told News24.Diplomatic passports are issued within strict guidelines and usually only applies for the specific purpose of the official's visit, immigration lawyer Craig Smith from Craig Smith & Associates told News24 on Wednesday.Grace Mugabe, the wife of Zimbabwe's President Robert Mugabe, was in SA to receive medical care for an injured foot, the Zimbabwe Mail reported.She allegedly assaulted 20-year-old model Gabriella Engels in a Sandton Hotel on Sunday, August 13."I doubt very much that a diplomatic passport was gazetted for her. Now that she's facing trumped up charges, Zimbabwean authorities are trying their level-best to find a way to get her off the hook," Smith said."If she did receive medical care on South African soil she would've further been required to get an additional visa from the Department of Home Affairs."READ: Grace Mugabe 'assaulted' me with an extension cord, model, 20, claimsNo clarificationDepartment of Home Affairs spokesperson Thabo Mokgola declined to clarify whether a medical visa was issued to Mugabe and referred all enquiries to the Department of International Relations and Co-operation (Dirco).Section 6.2 of the Diplomatic Immunities and Privileges Act 37 of 2001 (amended in 2008) reads: ''The Minister [of international relations] must by notice in the Gazette recognise a specific conference or meeting ..."It is unclear whether such a gazette ever appeared.When News24 asked Dirco spokesperson Clayson Monyela on Thursday about whether the gazette appeared or not, he declined to confirm or deny anything."I am referring your inquiry back to the police. Let's end the conversation. I don't have anything further to add on this matter."However, when News24 told Monyela that both the SA Police Service and the Department of Home Affairs had directed all queries to Dirco, he responded by repeatedly saying: "I don't have anything to add on this matter. I wish I could assist you, but I really am not in a position to assist you."He then referred News24 back to the police for further comment on Mugabe's status in the country.READ: Police don't know where #GraceMugabe is - AS IT HAPPENEDDiplomatic immunityNational police spokesperson Colonel Vish Naidoo told News24 that nobody had been arrested or questioned yet for the Engels assault and referred questions on whether the immunity had been granted to Dirco.''No I can't answer that. We don't grant diplomatic immunity,'' said Naidoo, when informed that Dirco had referred any questions to the police.According to attorney Ulrich Roux, diplomatic immunity is not automatic.''You need to apply for it,'' said Roux, a director at BDK Attorneys.Circumstances for applying for diplomatic immunity could include not being aware that an action was a crime in another country, or if the crime was committed in furtherance of their own country's interests.It is extended only to a diplomat such as a president, or to people close to the president's Cabinet, and then only if they are on diplomatic duty.An example would be if they had been sent to a country by their own country in order to further their own country's trade negotiations."In other words, a diplomatic trip," explained Roux."Obviously, this is not the case of Grace Mugabe. She is not part of a president's diplomatic party."LawlessnessRoux said Grace Mugabe should be subjected to normal processes and be investigated.Anything else would result in lawlessness around the world by diplomats' families, concluded Roux.Mugabe could face a charge of assault for the beating.Police Minister Fikile Mbalula previously said Mugabe was expected to appear in court on Tuesday, August 15, but on Wednesday the police ministry said the 52-year-old first lady never handed herself over to police."The suspect remains in South Africa," the police ministry said in a statement on Wednesday afternoon.The ministry said Grace Mugabe is expected to attend a Southern African Development Community (SADC) meeting underway in Pretoria, as well as attend to "personal matters".