Manuela Herzer could publicly question the mental competency of Redstone, who controls 80% of both CBS (CBS) and Viacom (VIA) through family company National Amusements, according to The Hollywood Reporter, which cites anonymous sources, as well as Herzer’s lawyer.

Redstone reportedly cut ties with Herzer last month while welcoming estranged family members back into his life, including his daughter, Shari Redstone, the vice-chair of CBS and Viacom. (Redstone also kicked out another former girlfriend, Sydney Holland, who had been caring for him with Herzer for years.)

Now Herzer could be gearing up to face off with Redstone’s family in a potential lawsuit that could offer some insight into the current mental state of a man who The Hollywood Reporter describes as “frail,” yet who holds sway over two giant media entities worth more than $40 billion combined. Redstone himself is reportedly worth more than $6 billion.

A source close to Herzer told The Hollywood Reporter that Redstone “is in twilight mentally,” while Herzer’s lawyer, Pierce O’Donnell, told the publication, “We are monitoring this fluid situation on a daily basis.”

Redstone’s lawyer called the idea of him requiring Herzer’s care “absurd” in a statement to The Hollywood Reporter. “Only Ms. Herzer would interpret Mr. Redstone’s decision to evict her from his home as evidence of diminished capacity,” said Gabrielle Vidal. “This has nothing to do with Ms. Herzer’s concern for Sumner Redstone and everything to do with her concern for her own financial agenda.”

Whether the claims coming from Herzer’s camp are true or not, they are likely to only further stoke investor concerns over Redstone’s ability to oversee his media empire. The Wall Street Journal wrote about those concerns in October, though the paper noted that Redstone has passed multiple mental competency tests, including one in recent months.