KAMPALA, Uganda—The family of a young model allegedly attacked with an extension cord by Zimbabwe’s first lady at a Johannesburg hotel has rejected a cash offer to drop charges against Grace Mugabe.

Pressure is mounting on Zimbabwe’s scandal-prone 52-year-old first lady—touted by some as a successor to her infamous 93-year-old husband—to face charges related to the assault of 20-year-old Gabriella Engels in the upmarket suburb Sandton on Sunday.

“This woman is not going to get off scot-free for what she did to my child,” the victim’s mother, Debbie Engels, said at a media conference Thursday.

“I know these people are not going to back down. They are going to fight… all the way,” Debbie Engels said.

The family was approached by a “third party” to accept a settlement, but no amount was mentioned, said former South African state prosecutor Gerrie Nel. The prominent lawyer secured the murder conviction of Oscar Pistorius and has offered the Engel family legal assistance.

Grace Mugabe is believed to still be in South Africa and police reportedly have issued a “red alert” at the country’s borders in case she decides to leave.

“If she is [still in the country], then she’s within this jurisdiction. If she’s not, if she’s escaped jurisdiction, we will really do what we can, in terms of the law, in terms of extradition if we can,” Nel told the press conference. He said he’d been told an arrest warrant for Mugabe was being sought.

Engels appears to have been visiting the first lady’s sons when the alleged attack happened. The model told News 24, Mugabe accused her of living with the sons. “She flipped and just kept beating me with the plug. Over and over,” Gabriella Engels told News24.

The model later posted a picture on Twitter showing a gash on her forehead, and subsequently appeared at a press conference with a bandage just below her hairline.

Grace Mugabe is seeking diplomatic immunity, which exempts heads of state, politicians, and diplomats from prosecution in a foreign country. Her husband, President Robert Mugabe, has arrived in South Africa ahead of a regional summit.

If immunity is granted to the first lady, South Africa risks a backlash—as was the case in 2015 when the country failed to arrest Sudan’s President Omar al Bashir for alleged war crimes.

The first lady, who is said to be positioning herself to succeed her husband as Zimbabwe’s president, is no stranger to controversy. Known for her extravagant shopping sprees before entering politics, she last year became embroiled in a dispute with a diamond dealer over a $1.35 million dollar ring.

This also isn’t the first time Grace Mugabe has been accused of assault. In 2009, the first lady was alleged to have assaulted a British photographer in Hong Kong. In that case, diplomatic immunity saved the first lady.

But it may not help her this time. A criminal attorney told Reuters that diplomatic immunity would not apply if Ms. Mugabe had entered on private business, which is said to be the case.

But South African authorities could still decide not to prosecute. The country may not want to risk a diplomatic row with Zimbabwe. And that could be be the first lady’s saving grace.