AP Photo/Evan Agostini, File

Kerry Kennedy, the ex-wife of New York Governor Andrew Cuomo, was arrested and charged with driving while impaired after she collided with a tractor trailer and left the scene of the accident, police said.

Police later found Kennedy, who is the daughter of the late Robert F. Kennedy, parked off an interstate north of New York City and passed out behind the wheel of her Lexus on Friday.

ABC News has learned that Kennedy told police she had been taking Ambien sometime that morning. But in a statement released by her family, they said there were no drugs involved.

"Kerry Kennedy voluntarily took breathalyzer, blood and urine tests - all of which showed no drugs or alcohol whatsoever in her system. The charges were filed before the test results were available," the Kennedy family said in a statement released to ABC News.

Kennedy has no known history of substance abuse, however many of her siblings have battled alcohol and drug issues. In May 2006, her cousin, former Rhode Island Rep. Patrick Kennedy crashed into a barrier near Capitol Hill, saying he had been disoriented after taking Ambien.

It has been a difficult few months for Kerry Kennedy. In May, her sister-in-law and best friend, Mary Richardson Kennedy, hanged herself in her Bedford, N.Y. home.

"She was an angel who was brought to us to live with us here on earth and I think that God just brought her back up to heaven and said 'you don't have to fight for us anymore'" Kerry Kennedy said of her friend.

Kennedy lives in Bedford, N.Y. and is the president of the Robert F. Kennedy Center for Justice and Human Rights.

ABC News' Richard Esposito contributed to this report