The late champion boxer Muhammad Ali sent a condolence letter to Mary Jo Kopechne’s father after her death 50 years ago, telling him to sue Ted Kennedy “for everything he’s got,” her family said.

The Kopechne family, whose 28-year-old daughter Mary Jo drowned July 18, 1969, after the car driven by Kennedy careened off a bridge into the water, had never shared the letter publicly before, the Times Leader reported.

The short, handwritten letter is dated July 31, 1969, to Joseph Kopechne, who died in 2003. He signed it “Muhammad Ali Cassius Clay.” The letter was released by cousins of Mary Jo Kopechne.

“Dear Mr. Kopechne, assert yourself in the interests of the good name of your daughter. Get yourself a good lawyer and sue that no good son of a bitch, Edward M. Kennedy, for everything he’s got,” Ali wrote.

Her name is Mary Jo Kopechne. https://t.co/QtVCwm6ylP — The News Leader (@NewsLeaderNOW) July 16, 2019

“There were no mitigating circumstances. His TV speech was written for him by a dozen lawyers and speechmakers, and was not his own. The cheap two-bit hypocrite! Sincerely, Muhammad Ali Cassius Clay.”

Experts at Beckett Collectibles authenticated the letter, according to Kopechne’s cousin William Nelson. He said Beckett spent hours matching up handwriting and signature as it would have been in 1969 when the letter was written.

“There was a bit of shock when they first saw it,” Nelson told the Daily Caller News Foundation. “Because they never knew it existed before.”

Kennedy eventually pleaded guilty to leaving the scene of an accident. (RELATED: ‘Chappaquiddick’ Is A Brutally Honest Movie Laying Bare The Kennedys For Who They Really Were)

Muhammad Ali died in 2016.

The Kopechne family said they waited to release it because they didn’t want a negative letter to reflect badly on the sender, but in the case of the Ali letter they felt it was time to ‘thank those who came to her defense those many years ago.’

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