Toxicology tests completed in June revealed that Mary Kennedy, 52, had the antidepressants Trazodone, Desmethylvenlafaxine and Venlafaxine in her blood when she died, a representative of the Westchester County Medical Examiner said. No traces of alcohol were found, the report said.

Her family could not immediately be reached for comment.

Mary Kennedy, who has been described by friends and relatives as having long struggled with depression, was found hanged in a barn behind the family's home in the New York City suburb of Bedford on May 16.

The cause of death was ruled to be asphyxiation by hanging and the death was a suicide, according to her autopsy.

Mary Kennedy had four children by Robert F Kennedy Jnr, a lawyer and son of the late Senator Robert F Kennedy and nephew of the late President John F Kennedy. They filed for divorce in 2010 but the proceedings were not finalised.

Her death was the latest tragedy to strike the Kennedy family.

President Kennedy was assassinated in 1963 and his brother, Robert, suffered the same fate five years later. JFK's son, John F Kennedy Jnr, died in a 1999 plane crash along with his wife and sister-in-law.

Two of Robert F Kennedy's sons died: David of a drug overdose in 1984 and Michael in a 1999 skiing accident.