But after a two month trial, a Los Angeles jury acquitted a second doctor on all charges in what was seen by the defense as a victory for physicians who treat patients with chronic pain.
Smith's companion and lawyer Howard K. Stern was convicted on two counts of conspiracy for using false names to obtain prescription drugs for his lover, but was acquitted on seven more serious charges.
Smith's psychiatrist Khristine Eroshevich was convicted on four counts. A January 6 date was set for sentencing, and a spokeswoman for the Los Angeles District Attorney said the pair could get anything from probation to three years in prison.
The three were not charged in the 2007 death of Smith, known as a model, TV star and for marrying an 89-year-old oil billionaire, 63 years older than her, in the 1990s. She died at age 39 from an accidental prescription drug overdose.
Stern, Eroshevich and physician Sandeep Kapoor had all pleaded not guilty to multiple charges of fraudulently providing drugs and controlled substances to a known addict.
Their lawyers argued that Smith needed the drugs for legitimate purposes, including the caesarean birth of her daughter Danielynn in 2006 and the death of her adult son days after. She used fake names to protect her privacy, they said.
The jury reached its split verdict after 13 days of deliberations following a trial that saw the judge criticize prosecutors for being overly aggressive and throw out some of the original charges against the trio.
Prosecutors said the three conspired to provide the late fashion model and reality TV star with a cocktail of painkillers, muscle relaxants, anti-depressants and anti-anxiety drugs by writing or seeking prescriptions using several false names.
The defense said their clients cared for Smith and would not harm her, and argued she used the drugs to help her sleep and control severe pain.
"This is the right result, not just for Kapoor, but for patients everywhere," Kapoor's lawyer Ellyn Garofalo told journalists.
"This was a misplaced and ill-conceived prosecution," Garofalo added, saying law enforcement officials should focus their resources on illicit drug pushers who supply pills for nonmedical purposes.
Eroshevich told reporters that she had few regrets about helping Smith.
"She (Anna Nicole) had a lot of problems. She was a good person and a friend," the psychiatrist said.
The investigation was backed by California Attorney General Jerry Brown, running for governor in elections next week.
Brown has mounted a tough campaign against prescription drug abuse, and officials in his office helped investigate the 2009 death of Michael Jackson. The singer's personal doctor has been charged with the involuntary manslaughter of Jackson.
(Reporting by Jill Serjeant; Editing by Bob Tourtellotte and Jerry Norton)
