Doctors who prescribe hundreds of pills without medical justification, raking in millions of dollars, are the center of local and federal criminal charges.

April Rovero recently spoke at a high school in West Virginia, the state that leads in both opioid prescriptions and opioid-related deaths.

Nearly everyone in the audience knew someone affected by opioid addiction. Some of the students were in foster care because their parents died of an overdose.

Rovero’s son, Joey, died after mixing alcohol, Xanax, and oxycodone. He bought the pills after driving 360 miles with his fraternity brothers from Arizona State University, where he was a semester away from graduation in 2009.

Dr. Hsiu-Ying “Lisa” Tseng sold him the pills from her office in a strip mall in Los Angeles County. In February, Tseng was sentenced to 30 years to life for the overdose deaths of three patients, including Joey Rovero.

Tseng’s conviction for second-degree murder was a landmark one.

She became the first doctor in the United States to be convicted of murder for overprescribing medication to patients.

“We’ve reached an extreme level of closure. We feel very blessed,” Rovero told Healthline. “I talk to parents all over the country who never get a drop of closure.”

Drug dealers have often been targets of criminal prosecutions, but now doctors that routinely give out powerful and addictive prescription drugs without medical justification are facing lengthy prison sentences.

John Niedermann, a Los Angeles County deputy district attorney and prosecutor in the Tseng case, says he looks for a “holy cow moment” when investigating a doctor’s prescription patterns.

“Unfortunately, it’s not hard to find these moments,” he told Healthline.

In his first prescription drug case, that moment was when one office prescribed more painkillers in one month than the entire staff at Johns Hopkins Hospital.

Another involved an undercover police officer who received a prescription for painkillers and muscle relaxants using an X-ray of a dog.

In Tseng’s case, it was how often police or the coroner’s office was calling to let her know one of her patients had died. In one instance, it was eight days apart.

“Her prescribing didn’t change in the least,” Niedermann said.

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In the light of the opioid epidemic, which the U.S. Centers for Disease Control and Prevention (CDC) says is “doctor driven,” law enforcement officials are targeting doctors who are more than liberal with their prescription pads.

These so-called “pill mills” are under increased scrutiny as local, state, and federal agencies try to slow the growing drug overdose rate, namely by prescription painkillers.

The difference between pill mills and legitimate pain specialists is the volume of patients seen, prescriptions written, and limited medical exams. Most only accept cash payments.

On Wednesday, a psychiatrist practicing in Jonesboro, Georgia, was indicted on three counts of murder related to the overdose deaths of his patients.

Dubbed “Dr. Death,” authorities say 36 of his patients died as a result of his prescriptions, namely oxycodone, hydrocodone, fentanyl, and methadone.

According to an Atlanta Journal-Constitution investigation, the psychiatrist, Narendra Nagareddy, was known as the go-to doctor to get pills. Despite receiving warnings for years, he was able to continue to give out prescriptions. He was one of the top prescribing doctors in Atlanta.

Last week, three Philadelphia doctors were indicted by federal officials on a variety of charges related to a now-defunct National Association for Substance Abuse-Prevention & Treatment.

Prosecutors say more than 1,000 patients — many of them healthy drug dealers — went through the clinic each month paying cash for prescription drugs, mainly Suboxone and Klonopin.

In January, the U.S. Attorney’s Office in northern Texas announced the indictment of a doctor and pharmacist, among others, for allegedly running a $5 million pill mill and distributing hundreds of thousands of oxycodone and hydrocodone pills.

According to the indictment, ringleaders would recruit homeless or poor people, tell them what to say, take them to pain clinics, pay for their visits, buy their prescriptions from them, and even drive them to pharmacies to get the pills.

“The clinics provided the oxycodone prescriptions by hiring medical practitioners willing to write them even though the clinic owners, managers, and practitioners knew they were not issued for a legitimate medical purpose in the usual course of professional practice,” a press release states. “To avoid detection by law enforcement, clinic owners and managers, script ringleaders, drivers, and recruits, concealed and assisted others in concealing the illicitly issued nature of the prescriptions, the quantities of controlled substances obtained and distributed, and the amount of the drug proceeds.”

A Reno-based physician is among the latest facing charges amid accusations of running a pill mill. He and eight other co-defendants face federal charges, including one related to a death of a patient. The charges are related to an alleged prescription drug distribution ring, which includes oxycodone and fentanyl.

According to DEA estimates, the ring sold more than $8 million worth of prescription drugs over two years.

“I am not a pain management specialist but I am a family doctor that takes your pain issues seriously,” the doctor’s family clinic website says.

Tseng, too, said she wasn’t adequately trained in pain management but still prescribed painkillers by the hundreds to patients.

Besides criminal prosecutions, the U.S. government is suing some doctors for defrauding federal healthcare programs, like Medicare and Medicaid.

One suit includes a Tennessee chiropractor and a doctor who allegedly billed federal drug programs more than $1 million. Through four pain clinics, they allegedly took in $5 million.

Many doctors have expressed concerns that these types of cases should be dealt with by state medical boards, not criminal courts. They fear a “chilling effect” that would prevent well-meaning doctors from prescribing medication to patients with legitimate medical concerns.

Addressing the Federation of State Medical Boards recently, Niedermann told them he’s not a witch hunter knocking on doors. Instead, he says he prosecutes cases that are “so off the reservation that they’re not even close to the profession of medicine.”

“If you’re doing your job, you have nothing to worry about,” he said. “If you’re not breaking the law, you don’t have to look over your back.”

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Tennessee, like West Virginia, has a major prescription problem.

These two states along with Alabama, Kentucky, and Oklahoma, all had more prescriptions for painkillers than people in pain — 128 prescriptions for painkillers per 100 people in 2012, according to CDC numbers.

At one point, Florida was the epicenter of pill mills.

State and federal agencies began targeting there in operations dubbed Operation Pill Nation and Operation Oxy Alley.

Florida pill mills were so successful for so long because of liberal drug enforcement laws as well as a lack of prescription drug monitoring programs. At one point, pain clinics were advertising in the back of newspapers and had customer rewards programs.

The pills would make their way across the country to states with stricter drug control policies. Often, people would drive from neighboring states to doctors who would prescribe pills with little medical justification, as was the case with Joey Rovero.

Then, in 2010, Florida began regulating pain clinics and prevented doctors’ clinics from dispensing medications directly from their offices; a practice experts say promoted high volume drug distribution.

As a result, by 2012, the state saw a 50 percent decrease in oxycodone prescription deaths.

But it was short lived. As many people feared, the pill mill crackdowns lead to a surge in heroin use and overdoses. As heroin is a cheaper opioid painkiller, many addicts turned to it to curb withdrawal symptoms and to continue to get high.

A study released last year found the pain clinic reform and enforcement reduced deaths from prescription painkillers and slowed heroin overdoses for a few years before surging again in 2013 and 2014, according to The Washington Post.

In September, a Florida jury acquitted an 81-year-old doctor in the death of a patient related to Operation Oxy Alley.

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More people died of opioid drugs in 2014 than in any other year.

They cross gender, race, and age boundaries, affecting nearly every demographic. That year, 28,000 people died from an opioid overdose, half of which involved prescription opioids.

Following her son’s death, Rovero learned more about opioid painkillers and the epidemic of addiction and overdose deaths they’re causing.

She founded the National Coalition Against Prescription Drug Abuse (NCAPDA), and now is an advocate for change in prescription drug policy, addiction treatment, education, and outreach.

“It’s not uncommon for me to get calls from parents who lost a child to a doctor who overprescribes or runs a pill mill,” Rovero said.

While these deaths affect more than just those who took the pills, only a small fraction of family members get to face those who willingly sold the powerful and addictive drugs merely for profit.

For those who do, it’s cathartic, Niedermann says.

“I think it is kind of a relief since many parents feel kind of responsible for what happened to their children, even though they didn’t have the skill set to deal with something like this,” he said. “It helps them put it into perspective.”