Bahamian police investigating the death of Anna Nicole Smith's 20-year-old son recently traveled to California, where they interviewed the young man's doctor and other people, an officer said Monday.

The four officers, who returned from the U.S. on Sunday, were seeking information about the days before Daniel Smith arrived in Nassau, where he died Sept. 10 in the hospital where his reality TV star mother had given birth three days earlier.

"We don't have any information to cause us to change our statement that no criminality was involved," Reginald Ferguson, assistant commissioner for the Royal Bahamas Police Force, told The Associated Press late Monday.

Ferguson said the officers interviewed a doctor for Smith, who died from a lethal combination of methadone and two antidepressants, according to a doctor who conducted a private autopsy. Smith had a prescription for the antidepressant Lexapro, but his family did not know the source of the other drugs, the doctor said.

Ferguson declined to say whom else the Bahamian officers spoke with or how much time they spent in California.

"They went to make inquiries relevant to the case, speaking to physicians and whomever else," he said. "You're looking for anything you can find that can be evaluated as part of the evidence. "

Ferguson said the officers received assistance from local law enforcement authorities in California, whom he declined to identify.

Smith boarded a flight in California to visit his mother and newborn half-sister, arriving in Nassau the night of Sept. 9. Police had been interested in speaking with anybody who sat beside him on a plane, Ferguson said.

Ferguson said police expected to complete their investigation as early as this week, before submitting a report to authorities who will determine whether a jury inquest into the death is necessary.

Smith's body is being held by a funeral home in the Bahamas awaiting instructions from the family on burial arrangements.