(CNN) -- Mary Richardson Kennedy, the estranged wife of Robert F. Kennedy Jr., had no traces of alcohol in her system when she took her own life in May, according to a toxicology report released Friday by the Westchester County medical examiner.
Kennedy, who had been battling depression, was found dead May 16 in Bedford, New York, a small town north of New York City where she lived. The medical examiner's office determined Kennedy died as a result of asphyxiation due to hanging. She was 52.
While no traces of alcohol were found in Kennedy's system, the medical examiner's report did find Trazodone, O-Desmethylvenlafaxine and Venlafaxine -- substances the National Institute of Health categorizes as anti-depressants.
Mary Kennedy married Robert F. Kennedy Jr. in 1994. The prominent environmental lawyer is the third of 11 children born to Ethel and Sen. Robert F. Kennedy, who was gunned down in 1968.
Details of the couple's private life were exposed when Robert Kennedy filed for divorce in May 2010.
After that, Mary Kennedy was charged once with driving while intoxicated and once with driving while impaired by prescription drugs, according to Bedford police.
"A lot of times, I don't know how she made it through the day," Robert Kennedy told The New York Times. "She was in a lot of agony for a lot of her life."
Despite the divorce filing, the couple were still married at the time of Mary Kennedy's death, her family attorney, Kerry A. Lawrence, told CNN in May.