A coroner cast doubt last night on a claim by the mother of Anna Nicole Smith that the troubled tabloid celebrity died from a drug overdose.

The Broward County Medical Examiner in Florida issued his preliminary findings as a court battle erupted on the other side of America over Ms Smith’s baby daughter, who could inherit almost half a billion dollars.

Virgie Arthur, Ms Smith’s mother, asserted that the 39-year-old former Playboy Playmate of the Year was “too drugged up” and suggested that she had suffered the same fate as her 20-year-old son, Daniel, who died of a drug overdose in the Bahamas last year.

“I think she had too many drugs, just like Danny,” Ms Arthur told the ABC Good Morning America programme. “I tried to warn her about drugs and the people she hung around with. She didn’t listen.”

Ms Arthur questioned why Howard K. Stern, her daughter’s boyfriend, had not saved her. “She was allowed to do drugs and for some reason he didn’t get her help in time this time,” she said.

“What that reason is, I don’t know. But before, whenever she would overdose, he always got her to hospital in time. What happened this time? Where was he?”

Police said that they had found prescription medicines but no illegal drugs in her room. But Joshua Perper, the Broward County coroner, said last night that a six-hour postmortem examination found no pills in Ms Smith’s stomach, as would be expected if she had taken an overdose.

He said that there was no trauma to the body except for a minor bruise on her back that he attributed to a fall in the bathroom several days ago.

Dr Perper said that it would take five to seven weeks to obtain the results of toxicology tests, adding that, while they were not ruling out a drugs overdose, they would be carrying out a microscopic analysis of “something that looks a little bit unusual” that could indicate a heart defect. Ms Smith had been suffering from a fever apparently related to stomach flu in the days before her death.

Authorities say that a private nurse found Ms Smith “unresponsive” in her room at the Seminole Hard Rock Hotel and Casino on Thursday.

The Access Hollywood website reported that the employee had pulled back the sheet to find that Ms Smith had choked on her own vomit. The website said that Ms Smith had taken a “children’s sedative” and “kept passing out” before she died. Ms Smith’s death left her five-month-old daughter, Dannielynn, at the centre of a legal tug-of-war potentially worth almost half a billion dollars.

Ms Smith recently won a Supreme Court judgment reviving her $474 million (£243 million) claim to the estate of her late husband, J. Howard Marshall II, a Texas oilman 63 years her senior, who was wheelchair-bound when he married her after seeing her in a strip club.

Dannielynn, who now stands to inherit her mother’s eventual share of the fortune, is at the centre of a paternity row between Mr Stern and Larry Birkhead, an ex-boyfriend.

Dannielynn’s birth certificate lists Mr Stern as the father. But Mr Birkhead stepped up his legal challenge yesterday by seeking an emergency court order to obtain DNA from Ms Smith’s body. The judge refused the request, but ordered that the body be preserved until a hearing on February 20.

The paternity row became even stranger yesterday when Prince Frederick von Anhalt, the husband of the actress Zsa Zsa Gabor, claimed that he might be the father of the child. Prince Frederick, 59, said that he and Ms Smith had been having an affair since the 1990s.

The baby is reportedly being cared for in the Bahamas by the mother of Shane Gibson, the Bahamian Immigration Minister, who was a close friend of Smith.

Daughter’s paternity in dispute

Anna Nicole Smith’s legacy could take years to untangle and could leave her baby daughter with millions of dollars — or nothing at all. Smith’s battle over the oil fortune of her late husband, J. Howard Marshall II, grinds on in Texas.

Pending legal action seeks unspecified damages against Smith and TrimSpa Inc, alleging that the company’s marketing of a weight-loss pill, with Smith as spokeswoman, was false and misleading.

Three men are contesting the paternity of Dannielynn, right, Smith’s five-month-old daughter. Howard K. Stern, a lawyer who is Smith’s most recent companion, is listed on the child’s birth certificate as her father. If it is determined that he is the biological father and he was married to Smith — yet to be established — he, not Dannielynn, would be likely to inherit Smith’s estate.

Larry Birkhead, Smith’s former boyfriend, and Prince Frederick von Anhalt, the husband of Zsa Zsa Gabor, each claim paternity of the child.

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