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(The Hill) – Caroline Kennedy, former President John F. Kennedy’s daughter, told senators in a letter that her cousin, Robert F. Kennedy Jr., President Trump’s nominee to serve as secretary of Health and Human Services, is a “predator” who has lied and cheated his way through life.

Kennedy said she hadn’t previously denounced her cousin’s nomination because she had been U.S. ambassador to Australia and was also reluctant to publicly criticize a family member.

But with RFK Jr. set to appear before the Senate Health, Education, Labor and Pensions (HELP) Committee this week, Caroline Kennedy said she felt “an obligation to speak out.”

She said that her cousin “lacks any relevant government, financial, management or medical experience” to qualify him to lead the nation’s health agencies — but added that his “personal qualities” pose “even greater concern.”

“I have known Bobby my whole life; we grew up together. It’s no surprise that he keeps birds of prey as pets because he himself is a predator,” she wrote in a letter to the chairmen and ranking members of the Senate Finance and HELP committees.

“I watched his younger brothers and cousins follow him down the path of drug addiction. His basement, his garage, and his dorm room were the centers where drugs were available, and he enjoyed showing off how he put baby chickens and mice in the blender to feed his hawks. It was often a perverse sense of despair and violence,” she wrote.

She acknowledged that people “can grow and change” and expressed admiration for his ability to pull himself out of “illness and disease,” referring to his bouts with addiction.

But she said that siblings and cousins “who Bobby encouraged down the path of substance abuse suffered addiction, illness, and death while Bobby has gone on to misrepresent, lie and cheat his way through life.”

She criticized him for making money from his “crusade against vaccinations” and warned that “he will keep his financial stake in a lawsuit against an HPV vaccine.”

“In other words, he is willing to enrich himself by denying access to a vaccine that can prevent almost all forms of cervical cancer and which has been safely administered to millions of boys and girls.”

She accused her cousin of expropriating her own father’s image and distorting his legacy to “advance his own failed presidential campaign.”

“Unlike Bobby, I try not to speak for my father — but I am certain that he and my uncle Bobby, who gave their lives in public service, and my uncle Teddy, who devoted his Senate career to improving health care, would be disgusted,” she wrote.

Robert F. Kennedy Jr. will appear before the Senate Finance Committee on Wednesday in his bid to become Trump’s health secretary. Another hearing for his nomination will be held on Wednesday in front of the Senate Health, Education, Labor and Pension committee, the panel his uncle, Ted Kennedy, once chaired.

The Associated Press contributed to this report.