LONDON: The father of Anna Nicole Smith's daughter Dannielynn has been subpoenaed to testify in a criminal case against his one-time love rival.

Larry Birkhead has since patched up his differences with the model/actress' companion Howard K. Stern and the two are now friends, but the photographer who fought with Stern over custody of Smith's baby could land the lawyer in trouble when he takes the stand in a preliminary hearing into the late star's drug use.

The hearing began in a Los Angeles courtroom on Tuesday (13Oct09).

Stern and associates Dr. Khristine Eroshevich and Dr. Sandeep Kapoor have been charged with conspiracy to furnish tragic Smith with drugs. All three have pleaded not guilty.

California Department of Justice narcotics investigator Danny Santiago opened the hearing by recounting what he discovered in the Florida hotel room where Smith collapsed before her death in February 2007.