Over 600 pills were legally prescribed to Ms Smith by Dr Eroshevich including around 450 muscle relaxants.
However the medic in question is now the subject of an investigation by the California medical board. Little is known about the case due to the private nature of the medical arbiter.
"I can only tell you that she [Eroshevich] is being investigated in connection with the Anna Nicole Smith matter," Candis Cohen, a board spokeswoman, told the Reuters news agency.
News of the investigation comes just weeks after police investigating the death announced that initial autopsy results were inconclusive and no illegal drugs were found in her hotel room.
The blonde bombshell, born Vickie Lynn Hogan, was once called the "next Marilyn Monroe" for her voluptuous figure and styling herself on the troubled actress for the cover of Playboy magazine.
Ms Smith rose to notoriety after her marriage to billionaire J. Howard Marshall in 1994 when she was 26 and the oil giant was aged 89. Mr Marshall died just over one year later, beginning Ms Smith's lengthy legal battle for a portion of his fortune.
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