Nina Mannering tried to quit, her mother said. She had a small daughter to care for. She was in a counseling program for a few months, but was told to leave when her boyfriend brought her pills. At one point, Ms. Mannering counted the number of schoolmates in four graduating classes who had died from overdoses, her mother recalled. The total was 16.

“It’s like being in the middle of a tornado,” said Ed Hughes, director of the Counseling Center, a network of rehabilitation and drug counseling clinics in the county. “It was moving so fast that families were caught totally off guard. They had no idea what they were dealing with.”

In January 2010, Ms. Mannering was killed less than a mile from her parents’ house. A man broke into the house where she was staying with a 65-year-old veteran who had access to prescriptions, and shot them both, looking for pills, the police said. She was 29. Her daughter, who was 8 at the time, watched.

“It was like your worst fear that could ever come true,” said Judy Mannering, who discovered her daughter’s body at dusk, bathed in the light of a flickering, soundless television. Her son, Chad, served three years in prison for robbery. He is now sober.

Families are joining forces to combat the problem. Mothers whose children died from addiction have started to picket clinics that they believed were reckless with prescriptions. Last month the City Council passed a moratorium on new clinics.

“If you look at the problem, it’s the darkest most malevolent thing you’ve ever seen,” said Terry Johnson, a former Portsmouth coroner who is now a state assemblyman. “But right now, people are feeling like they are making a difference, and that’s the most important thing. We need to capture that spirit.”

The authorities have had some successes. Last month, agents raided a doctor’s office and revoked his license. Another doctor from the area, Paul Volkman, is on trial in federal court in Cincinnati and accused of illegally disbursing prescription painkillers. But the drugs are legal, and it is hard to prosecute the people selling them. There are still five clinics in the county, several of them run by felons, officials said.