The Home Office has announced plans to cancel the identity cards and travel documents of former Miss South Africa finalist Chidinma Adesina and her Mozambique-born mother, both of whom could face fraud charges.
The department briefed a parliamentary portfolio committee on Tuesday and said the Hawks had taken over the investigation.
This comes in the wake of public scrutiny over Adesina's nationality, which arose when she became a Miss SA finalist a few months ago.
Director-General Tommy McCord said neither Mr Adesina nor his mother had responded by Monday's deadline to provide reasons for retaining the South African documents.
Officials reportedly visited Adesina's registered address in search of her mother, who is believed to remain in South Africa.
However, questions remain over her mother's reported trip to Nigeria last month to cheer on Adesina after she won the Miss Universe Nigeria title.
Images of the incident posted on social media suggest that Adesina's mother left South Africa during the investigation, despite there being no passport evidence of travel from Mozambique to Nigeria.
“No trace of the passport she used to enter South Africa from Mozambique regarding her trip to Nigeria was found,” said Albert Masaun, acting deputy director-general of the Immigration Department.
Meanwhile, social media updates indicate that Adesina recently left the United States for Mexico, where she will be representing Nigeria in the Miss Universe pageant.