By Lisa Richwine and Dan Levine
LOS ANGELES (Reuters) - Media mogul Sumner Redstone was under "undue influence" from people around him when he replaced his designated healthcare agent last fall, his ex-girlfriend argued on Thursday in her lawsuit challenging the elderly billionaire's mental competence.
The ex-girlfriend, Manuela Herzer, has sued over her removal as 92-year-old Redstone's healthcare agent in favor of Viacom Inc Chief Executive Officer Philippe Dauman. She claims Redstone was not mentally competent to make that decision in October 2015.
Herzer's attorneys said in a court filing on Thursday Redstone "is vulnerable to, and has become the victim of, undue influence, fraud, manipulation and chicanery."
Redstone gave up his roles as executive chairman of Viacom and CBS Corp (N:CBS) earlier this month. He still controls about 80 percent of the voting shares in both companies.
His attorneys have moved to dismiss Herzer's case, saying Redstone was fully aware of his actions and arguing that Herzer has filed her lawsuit for financial gain.
In October, Redstone also revoked a part of his estate plan that would have given Herzer a $70 million inheritance, his lawyers said in an earlier filing. Redstone instead directed those assets to his charitable foundation, they said.
A Los Angeles judge is set to consider on Feb. 29 whether to throw out Herzer's lawsuit.
In Thursday's filing, Herzer's attorneys said Redstone is "frail" and "isolated in a virtual intensive care unit." Daughter Shari Redstone "exploited his isolation" and "manipulated her incapacitated father to her own financial advantage," they said.
A spokeswoman for the daughter said: "Shari Redstone is not going to dignify today’s baseless and mean-spirited attack on the Redstone family with any comment."
Lawyers for Herzer also said a letter to the Viacom board that praised Dauman's leadership was a "fraud" written by Dauman himself but was portrayed as coming from Sumner Redstone. A Viacom spokesman had no comment.
Portions of Thursday's filing were redacted, including details of a Jan. 29 examination of Redstone by Stephen Read, a geriatric psychiatrist hired by Herzer.
There was no public indication Read had changed his opinion from November, when he filed a court declaration saying he believed Redstone lacked the mental capacity to change his healthcare directive.
Redstone's personal physician, Richard Gold, and geriatric psychiatrist James Spar have told the court they believe the mogul was competent to make that decision.