The chief magistrate says they're still waiting for their own toxicology findings. Those will determine if a jury inquest is necessary.
According to well-known American pathologist Dr. Cyril Wecht, the 20-year-old died from the "accidental" effect of methadone and two antidepressant drugs interacting in his system.
The low levels of the three drugs detected by toxicology tests indicated Daniel Smith died "a tragic, accidental, drug-related death," Wecht, who conducted a private autopsy, told The Associated Press on Wednesday.
But Bahamian officials says Wecht's results aren't "the official results," so they'll wait for their own.
In the meantime, Smith's body remains at a funeral home in the Bahamas.
He died Sept. 10 at his mother's hospital bedside in the Bahamas, where the reality TV star and former Playboy playmate was recuperating from giving birth to a daughter three days earlier.
Wecht said Zoloft, Lexapro and methadone had a lethal "cumulative effect on the central nervous system" that ultimately stopped Smith's heart — a "classical" death resulting from a combination of drugs without an overdose of any one.
"Oh my, that's a really lethal combination right there," said Lisa Johnson, a pharmacist at Cedars-Sinai Medical Center in Los Angeles. "If that's what he was on, it could very well have caused this."
"The methadone will slow you down, but the other ones make your system speed up, so it's an odd combination," she said in an interview.
Smith had reportedly been suffering depression related to a breakup with a girlfriend when he went to visit his mother and newborn half-sister in Nassau. Zoloft and Lexapro, which a U.S. doctor had prescribed, are antidepressants commonly used to treat anxiety and panic disorders.
But Wecht said he did not know why Smith was taking methadone, a pain-reliever that is also used to ease heroin cravings for recovering addicts.
"It is used for people who have been on heroin or morphine," Wecht said from his home in the Pittsburgh area. "I have made those inquiries. I can only say to you no one has suggested anything having to do with drug addiction in this boy."
A lawyer for Anna Nicole Smith said she hired Wecht, a forensic pathologist who gained fame as a consultant on celebrity cases including Elvis Presley's death, to end speculation about her son's death.