Coroner: Mary Kennedy, estranged wife of Robert F. Kennedy Jr., died of asphyxiation due to hanging

Robert F. Kennedy Jr. and Mary Kennedy are seen attending a gala fundraiser at the Deer Valley Resort in Salt Lake City in this Dec. 4, 2010 file photo. Mary Kennedy was found dead Wednesday, May 16, 2012, at her home in Bedford, N.Y., an apparent suicide.
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Updated at 3:01 p.m. ET

(AP) BEDFORD, N.Y. - Robert F. Kennedy Jr.'s estranged wife, Mary Richardson Kennedy, an architect known for her philanthropic and environmental work who also was hit with drug and alcohol charges in recent years, died of asphyxiation due to hanging, a medical examiner said Thursday.

A person familiar with the investigation into her death says that authorities have concluded that her death was a suicide. The person was not authorized to release the information and spoke on condition of anonymity. Bedford police have declined to answer questions about the circumstances of her death.

Kennedy's body was discovered Wednesday afternoon at the family's property in suburban New York. The Westchester County medical examiner's office performed an autopsy Thursday morning.

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Her death came after several hard years for the family. Her husband, Robert Kennedy Jr., a prominent environmental lawyer and the son of Sen. Robert F. Kennedy, had filed for a divorce in 2010. The two had married in 1994 and had four children together. The divorce case was still pending.

In the months after the couple's separation became public, Mary was arrested twice by police officers who suspected her of driving while intoxicated. Her license was suspended once, but a drunken driving charge was dismissed. Last July, a judge dismissed a charge of driving under the influence of prescription drugs, saying she hadn't been aware it could impair her ability to drive.

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On Thursday morning, people who knew the family, and some strangers, as well, dropped by home to leave flowers at the front door.

"I think every family has its tragedies. But this is too much. You have to feel for them," said Kim O'Connell, 59, of Bedford Hills, as she dropped off a bouquet of Calla lilies. She said she had met Mary and Robert while working at their health club.

"I just thought she was just a lady. I woke up this morning, and I wanted to do something," she said.

Both the Richardson and Kennedy sides of the family expressed sadness over her death in public statements that noted her "gentle soul and generous spirit," her work advocating environmentally responsible building designs, and her deep love for her children.

The family hasn't commented publicly on whether she had struggled with depression, or why she might have taken her own life.

Kennedy grew up in Hoboken, N.J., the daughter of a professor at the Stevens Institute of Technology. She had two brothers and four sisters.

Her own family had been intertwined with the Kennedys even before her storybook wedding aboard a boat in the Hudson River Valley in 1994. She met Robert's sister, Kerry Kennedy, at boarding school when they were teenagers, and was a maid of honor at her wedding to Andrew Cuomo, now governor of New York, in 1990. Mary's eldest sister, book editor Nan Richardson, was also involved in human rights causes with Kerry Kennedy, now divorced from Cuomo.

Mary Richardson Kennedy was active for years with the Boys & Girls Club in Mount Kisco, volunteering for the club's annual fundraising dinner and hosting its Youth of the Year awards at her home.

With one of her children battling severe allergies, Kennedy co-founded the Food Allergy Initiative, billed as the world's largest private source of funding for food allergy research, and appeared with her family at its annual ball at Manhattan's Waldorf Astoria.