Asked whether he could have taken steps to prevent any of the deaths, Vu paused.
"No," he said, finally. "I don't think so."
Larry Carmichael was a problem drinker who got sober through Alcoholics Anonymous. A doting single father, he coached his son's T-ball team and passed on his love of surfing and fishing.
Carmichael worked as a carpet layer until a car accident left him with debilitating back pain, recalled his son, Dan. He went from one doctor to another in search of relief, and eventually became Vu's patient.
By 2007, Carmichael "had a high tolerance and was known to take too many pills for his pain," coroner's records state. Renee Allen, Carmichael's girlfriend, said she encouraged him to see if he could live without the medications, and to find another doctor.
"I'm not going to sit around and watch you die," she recalled telling him.
But Carmichael kept taking pills. In the months before he died, Carmichael twice passed out, his son said.
"He needed real help," Dan said.
On March 7, 2007, Carmichael filled prescriptions from Vu for half a dozen pain and anxiety medications, including morphine, according to coroner's records.
After Carmichael failed to return phone calls for two days, Dan went to his father's apartment in Lake Forest and found him dead. He was 51.
Dan grabbed his father's prescription bottles and smashed them against a wall, sending pills flying around the room, according to a report by a coroner's investigator.
The coroner concluded that Carmichael died of an accidental overdose of morphine.
For decades, prescriptions for narcotic painkillers were limited largely to cancer patients and others with terminal illnesses. The prevailing view was that the risk of addiction outweighed any benefit for the great majority of patients whose conditions were not life-threatening.
Today, narcotic painkillers are among the most popular prescription drugs in the U.S.
The seeds of this turnabout were planted in the late 1980s, when influential physicians argued in medical journals that it was inhumane to ignore suffering in non-cancer patients.
This new perspective coincided with efforts by drug makers to win approval for formulations of narcotics intended to ease moderate pain.
Pharmaceutical companies launched sales campaigns that downplayed the risks of addiction and overdoses and promoted the benefits of pain relief.
In 2001, Congress declared the start of the Decade of Pain Control and Research. Medical boards across the country encouraged physicians to assess and treat pain in all patients. In 2007, California lawmakers expanded the scope of pain relief, making it legal for doctors to prescribe narcotics to addicts, so long as the purpose was to treat pain and not simply feed a habit.
The use of painkillers quadrupled between 1999 and 2010. Doctors write about 300 million prescriptions a year for painkillers. That is enough for every adult American to be medicated around the clock for a month, according to the Centers for Disease Control and Prevention.
Hydrocodone became the most commonly prescribed drug in the U.S., eclipsing the leading antibiotics and cholesterol medications.