Anna Nicole Smith, right, leaves US Supreme Court in Washington with her son Daniel Smith in this February 28, 2006 photo

A medical examiner in Florida says he has not determined the cause of death following an autopsy on former Playboy model Anna Nicole Smith, who died Thursday.

The examiner told reporters Friday that the autopsy was able to rule out physical injury as a cause.  He also said there was no indication that the famous model overdosed on prescription drugs found in her hotel room Thursday.

He called the case a "medical puzzle" and said it would take three to five weeks to conclude the investigation.

Authorities say paramedics tried to revive the 39-year-old Smith after she was discovered unconscious Thursday in her hotel room in Hollywood, Florida. 

Besides modeling, Smith appeared in movies and a reality television show.
 
Smith was 26 years old in 1994 when she married 89-year-old oil billionaire J. Howard Marshall.

His death set off a legal battle between Smith and Marshall's son, with the U.S. Supreme Court ruling that Smith could pursue part of Marshall's oil fortune.

Smith's sudden death comes just five months after her 20-year-old son, Daniel, died in the Bahamas three days after she gave birth to a daughter.  The paternity of the child remains in dispute. 

Smith's mother, Virgie Arthur, told ABC television that drugs were likely to have contributed to her daughter's sudden death.

Some information for this report was provided by AFP and AP.