NEW YORK (Reuters) - The estranged wife of Robert F. Kennedy Jr. died from asphyxiation due to hanging, an autopsy revealed on Thursday, in an apparent suicide at the family's suburban New York home.

A spokeswoman for the Westchester County Medical Examiner's Office, Donna Greene, said the autopsy performed on Mary Kennedy, 52, revealed she died of suffocation.

"The cause of death was put at asphyxiation due to hanging," Greene said.

Results of toxicology tests would not be ready for several months, she said.

Kennedy was found hanging in a barn behind the family's home in the New York City suburb of Bedford on Wednesday, according to the New York Times and ABC News, which both cited unnamed sources.

The New York Times reported her body was cut down by authorities and attempts to revive her were unsuccessful. The Times said she had left a note.

Mary Kennedy had four children with Robert Kennedy, a lawyer and environmentalist who is the son of the late Senator Robert F. Kennedy and nephew of the late President John F. Kennedy.

"We deeply regret the death of our beloved sister Mary, whose radiant and creative spirit will be sorely missed by those who loved her," Mary Kennedy's family said on Wednesday in a statement released by her lawyer.

Mary and Robert Kennedy filed for divorce in 2010 but it had not been finalized, said Kerry Lawrence, a lawyer for Mary Kennedy.

(Reporting by Barbara Goldberg; Editing by Bill Trott and Vicki Allen)