When dozens of overdose victims who got painkillers from the same Kansas clinic started showing up at emergency rooms and the county morgue, federal prosecutors accused a doctor and his wife of indiscriminately writing prescriptions for powerful drugs at a so-called pill mill.

Two years later, as the trial of Dr. Stephen Schneider and his wife, Linda, draws to a close in Wichita, the case is shedding new light on medical treatment that some doctors portray as help for chronic pain sufferers but that federal authorities consider part of the illegal drug trade.

Prosecutors insist doctors such as the Schneiders are prescribing large amounts of drugs to make money, not to help patients in pain. Such doctors and others have helped make prescription painkillers second only to marijuana as the nation's most prevalent illegal drug problem, said Gary Boggs, supervising special agent for DEA drug diversion program.

"This is a case where the defendants were not only cheating people out of money but, more importantly, were cheating people out of medical services and for some people cheating them out of life," Assistant U.S. Attorney Tanya Treadway told jurors in her opening statement in the Schneiders' trial.

Nationwide, federal authorities have arrested more than 450 physicians in the last six years as part of a federal drug diversion program, according to Drug Enforcement Administration data. The Schneiders have pleaded not guilty to charges of unlawfully writing prescriptions, health care fraud and money laundering. If convicted, they face up to life imprisonment.

But defense attorneys said the Schneiders were experienced professionals providing pain relief for people suffering from severe injuries, the effects of surgery, migraine headaches and other medical conditions. In many cases, the couple served low-income Medicaid patients who had no other place to turn, they said.

Their defense has been supported by an advocacy group that represents chronic pain sufferers, who it contends are neglected by doctors and harassed by law enforcement. "This is really a civil rights issue," said Siobhan Reynolds, president of the New Mexico-based Pain Relief Network. Those who need pain treatment are "criminalized, abused, treated as subhuman," she said.

Probably fewer than 5,000 doctors are willing to prescribe high levels of opioids to treat pain, said Dr. Joel Hochman, executive director of the National Foundation for the Treatment of Pain, a Texas-based nonprofit that provides legal help for doctors.

Schneider, 56, and Linda, 52, a nurse and human resources manager, operated the Schneider Medical Clinic, a sprawling facility with 14 examination rooms in the Wichita suburb of Haysville.

Prosecutors allege the Schneiders regularly dispensed OxyContin, fentanyl, hydrocodone and other powerful drugs to patients with severe pain but also to drug abusers who feigned symptoms. Schneider did not monitor cases carefully, prescribed excessive dosages and wrote prescriptions so freely he became known among some patients as the "Candy Man," prosecutors said.

The patients included Patricia Gaskill, 49, who was suffering from pain after knee replacement surgery in 2005. Two days after she was released from the hospital following an apparent drug overdose, the clinic gave her another prescription for the same drugs. She died two days later. Another patient, Robin Geist-Wick, 45, died in 2007 after she went to the clinic complaining of migraine headaches. She was prescribed a potent drug only approved for terminal cancer patients, prosecutors said.

Prosecutors have alleged that drugs prescribed by what they called the "pill mill" led to 68 deaths and many overdoses. The deaths included suicides and cases of accidental mixed drug intoxication. The Schneiders' clinic collected more than $4 million from private insurers, government programs and patients between 2002 and 2007, when it closed.

Schneider insisted he provided prescriptions only to patients he thought needed them and cut off those he suspected were abusing or selling the drugs. "I never wrote a prescription to any patient I didn't think the medication would be helpful to them," he told jurors.

In the case of Geist-Wick, he said, the drug he prescribed _ Actiq, a lollipop form of the painkiller fentanyl _ was marketed for off-label treatment of migraines. The defense also suggested that pre-existing cardiac problems, not drug overdoses, may have caused some patients' deaths.

Myra Christopher, president of the Center for Practical Bioethics in Kansas City, Mo., a research center on medical ethics issues, said most government prosecutions appear to be well-founded but that the enforcement is having a "chilling effect" in the legitimate prescribing of painkillers.

"Physicians are very sensitive about these cases and when these cases get a lot of media attention ... it compels them to believe their fears are right," said Christopher.