The conclusion by Dr. Govinda Raju, who performed the official autopsy on Daniel Smith, confirms the findings of a private doctor who examined the 20-year-old's body after he died Sept. 10, 2006 in the Bahamas.
On the third day of an inquest into Smith's death, Raju said the young man had five other drugs in his system - including two that medical personnel used in an attempt to revive him after he collapsed while visiting his celebrity mother at a Nassau hospital.
The former Playboy playmate herself collapsed and died Feb. 8 in Florida from an overdose of drugs.
A lawyer for Anna Nicole Smith's attorney-turned-boyfriend Howard K. Stern, who was also in the hospital room the day Daniel died, said the drugs he was taking were all for either depression or back pain.
"Once you boil it all down, these were medicines treating either pain or depression," said the attorney, Wayne Munroe.
Zoloft and Lexapro, which a U.S. doctor had prescribed, are antidepressants commonly used to treat anxiety and panic. Methadone is prescribed as a pain reliever and is also used to suppress symptoms drug users experience when going through withdrawal from heroin and other opiates.
Cyril Wecht, the doctor who performed a second autopsy at the request of Smith's family, has said the other drugs in Daniel's system included a third antidepressant, the sleep medication Ambien and an over-the-counter cold medicine. He said they did not play a role in his death.
Daniel Smith had bruises on his back and shoulders, but Raju said these could have been caused by medics who tried to revive him. Police have said there is no evidence of homicide.
Police believe he arrived in the Bahamas the night before his death and went directly to the hospital where his mother had given birth two days earlier. He spent the night in a room with his mother, Stern and newborn half-sister before losing consciousness.
Testimony is scheduled to resume Tuesday.