Anna Nicole Smith's son was on prescription anti-depression medication when he died at the hospital bedside of the former reality TV star, a pathologist who did a second autopsy on 20-year-old Daniel Smith said Monday.

Forensic pathologist Cyril Wecht said Daniel Smith was being treated for depression that began about four to six weeks earlier, but he did not know whether the medication played any role in his death, which came three days after his celebrity mother gave birth in the Bahamas.

Wecht, speaking by phone from Miami a day after conducting the autopsy in the Bahamas, said he's still awaiting toxicology tests to determine the cause of death.

Click Here for the Anna Nicole Smith Celebrity Center

He said he and the Bahamian coroner who did the first autopsy agreed there was no evidence that Daniel Smith died from a "suicidal overdose."

Smith died Sept. 10 in the hospital room where the former Playboy model was recuperating from giving birth to a daughter.

Wecht said he spoke to the psychiatrist who treated Daniel Smith and was told the dosage of the antidepressant medication was "quite low" and that the depression "had to do with a girlfriend."

He did not provide further details and said others, including Anna Nicole Smith's attorney Howard K. Stern, said Daniel Smith had seemed to be in good spirits in the days before his death.

"He was delighted. He was happy to be there with his mother and his sister," Wecht told The Associated Press.

Earlier, Wecht said the autopsies have ruled out several natural causes and that the results of the drug and chemical analyses could take weeks. Investigators have said they did not find evidence of drugs in the room or obvious signs of a crime.

Wecht, who gained fame as a consultant on celebrity cases including Elvis Presley's death, ruled out several potential natural causes including heart disease, stroke, or a "congenital anomaly." He also said there was no indication of foul play.

"I don't find anything that would cause me to believe there is something in terms of some traumatic injury having been inflicted, or somebody having done something to him in some cryptic manner that could not be observed," he said.

Bahamian pathologists performed an autopsy Tuesday and were expecting toxicology results this week, but the coroner's office has said the findings will not be released before a jury inquest scheduled for Oct. 23.

Smith ordered the follow-up autopsy to end "media speculation surrounding the matter," said her Bahamian attorney, Michael Scott.

Head Bahamian coroner Linda Virgill said it was not unusual for families to ask for an independent examination.

A hearse took Smith's remains from the morgue to a funeral home making arrangements to return the body to California.

Wecht, 75, is facing trial on charges he used his staff when he was the coroner in Allegheny County, Pa., to do work for his multimillion-dollar private pathology practice. He resigned from office in January and contends he did nothing wrong.

He received international prominence as a critic of the Warren Commission's single-gunman theory of President Kennedy's assassination.

Smith, 38, who came to the Bahamas during her pregnancy to avoid media scrutiny, is free to leave the Caribbean island chain, authorities have said.

Scott said Smith was not prepared to speak with the media.

"She is depressed and she's at home, and remember that she's got a new child that she's looking after," he said.

Daniel Smith, who appeared several times on the E! reality series "The Anna Nicole Show," was the son of Anna Nicole and Bill Smith, who married in 1985 and divorced two years later.

The identity of the father of her newborn daughter has not been publicly released.

Smith married Texas oil tycoon J. Howard Marshall II in 1994, when she was 26 and he was 89. He died the following year and she has since been involved in legal disputes over the estate.

Click Here for the Anna Nicole Smith Celebrity Center