One Orange County mother told us about the moment she learned her only son Riley was dead.
"I dropped to my knees, and I just went into shock," Leslie Vaughn said.
Her son's overdose is one of at least 19 deaths linked to Dr. Lisa Tseng.
The Rowland Heights now former physician is facing trial on three counts of second-degree murder in the overdose deaths of Joey Rovero, Steven Ogle and Vu Nguyen. She has pleaded not guilty.
But six more dead Tseng patients are named in the criminal complaint that lists felony charges against Tseng for unlawful prescription.
"I blame her for a lot of it. There's just too many, there's too many," Vaughn said.
Pharmacy records show that Tseng prescribed Opana, Soma and Xanax to Vaughn's son in 2009. Tseng settled a wrongful death lawsuit with Riley's family; it's one of 12 wrongful death lawsuits Tseng has settled so far.
"This is a club you don't want to join," Vaughn said. "All these kids are connected, that common thread."
But there's another apparent connection among many of Tseng's former patients, and that's Pacifica Pharmacy in Huntington Beach.
According to medical and coroner records obtained by Eyewitness News, at least seven of Tseng's now dead patients, including Riley, traveled to a tiny pharmacy on Beach Boulevard to fill their prescriptions for narcotics like OxyContin, Opana and Xanax. A man who only wanted to be identified as Robert says it's because not a lot of questions are asked at the pharmacy.
"Just, 'Here's my prescription, here's my cash. Fill it for me please, I'll be back in 10 minutes,'" he said.
Robert is now three-and-a-half years sober, but he recalls the connection between Tseng's office in Rowland Heights and Pacifica Pharmacy, which is more than 30 miles away.
"You'd run into the same people that you see up at Dr. Tseng's, you know, that like you were sitting in the waiting room with for the last two or three hours," Robert said.
Robert would get high in the parking lot outside Pacifica Pharmacy and pay for his prescription drugs with large sums of cash - anywhere from $1,200 to $2,700 in cash.
"I looked like a drug addict, you know what I mean," he said. "They had to know what's going on. There's no ifs, ands or buts about it."
According to an accusation filed by the California Board of Pharmacy, Pacifica Pharmacy filled 1,844 prescriptions for controlled substances written by Tseng over a one year period. The pharmacy board concluded that Pacifica -- and its owner and pharmacist-in-charge Frank Tran -- ignored red flags like large cash payments, early refills and patients traveling long distances to have their prescriptions filled, patients like Joey Rovero, then a senior at Arizona State University.
"He left from Arizona, traveled to Los Angeles, went to Dr. Tseng in Rowland Heights, and immediately went to Pacifica Pharmacy over in Huntington Beach," said his mother April Rovero.
Joey Rovero overdosed nine days later - dead at the age of 21.
"It is so hard every single day to think about him not being with us," April Rovero said.
The California Board of Pharmacy shut Pacifica down last year and revoked Tran's pharmacist license.
But Tran's attorney Armond Marcarian says Tran is the victim. Tran is appealing the board's decision. He refused repeated requests for an interview and refused to testify at his pharmacy board hearing.
When asked why so many of Tseng's painkiller patients ended up at Pacifica, Marcarian responded, "When you say 'so many,' I don't know how many patients she had, so one can make the argument why did so few of them go to Pacifica Pharmacy."
Attorney Larry Eisenberg represents eight local families who have settled wrongful death lawsuits against Tseng.
"It just doesn't make sense that all of these patients, just by chance, ended up at Pacifica Pharmacy. They had to be steered there. And most likely they were by Dr. Tseng," Eisenberg said.
The pharmacy board investigation began after a business owner just above Pacifica Pharmacy noticed suspicious activity in the parking lot like cash spread across a car dashboard and money and prescriptions changing hands.
"There were actually drug deals going on in the parking lot adjacent to the pharmacy," Eisenberg said.
There were red flags seemingly clear enough to that other business owner, but not to Tran.
"When you say red flags, it's always easy with the benefit of hindsight to see all these red flags," Marcarian said.
But that doesn't ring true for the families left behind.
"This is Riley. This is his box," Vaughn said as she held up his urn.
Ashes in an urn, handwritten notes and a valentine are what Vaughn holds onto.
"You don't get to say goodbye. You remember the last time you talked to him. And you hope you said enough," Vaughn said as she held back tears.
California has a database known as CURES that can track prescription drugs and could identify rogue doctors or pharmacists. But funding was cut by Gov. Jerry Brown in 2011. Right now, the CURES program is down to a single full-time employee.