NASSAU, Bahamas (AP) - An autopsy ordered by Anna Nicole Smith to determine what killed her 20-year-old son has ruled out several natural causes, but her pathologist said he needs to conduct more tests including drug and chemical analyses. 

Forensic pathologist Cyril Wecht, who gained fame as a consultant on celebrity cases including Elvis Presley's death, said the results of samples taken Sunday from Daniel Wayne Smith could take weeks to complete.