After Daniel Eckhardt’s corpse was found on the side of a road in Hamilton County, Ohio, last year, police determined he died of a heroin overdose.

Not long ago, law enforcement’s involvement would have ended there. But amid a national opioid-addiction crisis fueling an unprecedented wave of overdose deaths, the investigation was just beginning.

Detectives interrogated witnesses and obtained search warrants in an effort to hold someone accountable for Mr. Eckhardt’s death. The prosecutor for Hamilton County, which includes Cincinnati and its suburbs, charged three of Mr. Eckhardt’s companions, including his ex-wife and her boyfriend, with crimes including involuntary manslaughter, an offense carrying a maximum prison sentence of 11 years.

Mr. Eckhardt voluntarily took the heroin that killed him, but prosecutors alleged the trio were culpable because they bought and used heroin with him that they knew could result in death.

The indictments were part of a nationwide push to investigate overdose deaths as homicides and seek tough prison sentences against drug dealers and others deemed responsible. It’s an aggressive tactic law-enforcement officials say they’re using in a desperate attempt to stanch the rising tide of overdose deaths.

Fueled by a flood of heroin laced with fentanyl and other powerful synthetic opioids, the overdose death rate in Hamilton County more than tripled between 2006 and 2016 to 50 per 100,000 people, or four times as many as those killed in traffic accidents. Nationally, some 64,000 Americans died from overdoses last year, up 86% from 2006, according to the Centers for Disease Control and Prevention.

A newly created heroin task force in Hamilton County has investigated hundreds of deaths in the past two years, resulting in a dozen involuntary manslaughter indictments in state court and 13 federal indictments for distribution of controlled substances resulting in death.

“The deaths—that’s why. All the people dying,” Cmdr. Thomas Fallon, who leads the Hamilton County task force, says of the prosecution push. “Even in the cocaine and crack days, people didn’t
die like this.” At least 86 people nationwide received federal prison sentences last year for distributing drugs resulting in death or serious injury, up 16% from 2012, according to  the U.S. Sentencing Commission, a federal agency that determines sentencing guidelines  for judges. An analysis of news reports found 1,200 mentions nationally about drug-death prosecutions in 2016, three times the number in 2011, according to a recent report by the Drug Policy Alliance, a nonprofit group that supports decriminalizing drug use.

The prosecutions often employ tough-on-crime legislation born of the crack-cocaine epidemic of the 1980s and 1990s. These state and federal laws hold drug distributors liable for overdose deaths. Selling even small amounts can result in decades or even life in prison.

In some states, such laws were rarely enforced until recently. Benjamin J. Agati, a veteran prosecutor in the New Hampshire Attorney General’s office, has helped train police departments throughout the state in how to build cases under the state’s drug induced homicide law, which carries a maximum penalty of life in prison. The law was enacted in the late 1980s but was rarely applied before the surge in opioid deaths, Mr.
Agati says.

Before the current overdose crisis, the typical police response to a drug death was “ ‘OK, I gotta call the medical examiner, notify next of kin, make sure there’s no foul play and dispose of the needle. And then I’m outta here,’ ” Mr. Agati says. “It’s just another person who’s died from addiction and that’s it.”

In late 2015, a Justice Department task force recommended that law enforcement “prioritize prosecutions of heroin distributors, especially when the drug causes death.” Since 2013, Kansas and Delaware have passed laws that punish dealers for distributing drugs that result in death, and 13 state legislatures have introduced bills that would do the same, according to the Drug Policy Alliance.

But in courtrooms around the country, prosecutors are also sweeping up low-level dealers who are addicts trying to support their habit, as well as friends and family members of overdose victims who bought or shared drugs with the deceased. Some critics of the prosecution tactic say these users need treatment, not harsh prison sentences.

Critics see the prosecutions as more of the same drug-war tactics that have filled America’s prisons with nonviolent criminals but done little to stop illicit drug use. There’s scant evidence that fear of prison deters addicts from using, and for every dealer put behind bars, another is ready to take his place, says Lindsay LaSalle, an attorney with the Drug Policy Alliance.

Law-enforcement officials say they’ve seen some signs the prosecutions may be deterring dealers, including jailhouse phone calls they say they’ve overheard in which inmates warn associates that police are pressing homicide charges against drug traffickers. They say drug-death prosecutions are just one piece of a broader strategy to combat the crisis, including urging addicts into rehab and taking down large-scale
traffickers.

In Hamilton County, heroin addiction looms large. Cmdr. Fallon, the task force commander, is raising his grandson because his adult child is hooked. The daughter of another officer barely survived a heroin overdose earlier this year. A former county prosecutor, Allison Hild, pleaded not guilty earlier this year to charges of trafficking heroin.

The task force members, who are on call 24 hours a day to respond to overdoses, include officers from local police departments, the state Highway Patrol and a federal agent from the Drug Enforcement  Administration.

When Detective Mark Bohan’s cellphone woke him from a deep sleep late just before midnight one October night, he thought it must be his 4 a.m. alarm rousing him for the gym. Instead, it was a text message alerting him to a suspected heroin overdose.

Detective Bohan, a fit man with dark hair and a goatee, got dressed and drove to the scene, hoping to gather evidence that might lead him to the dealer who sold the fatal dose to the 26-year-old male victim.

On the porch of the two-story white house, Halloween decorations hung from the rafters and the dead man’s girlfriend smoked a cigarette. “I thought he was clean,” she sobbed. Detective Bohan, 49, searched the man’s cellphone for text messages that might point to where he bought the drugs. He asked the woman if she knew the name of her boyfriend’s dealer, but she could only give an address.

A few years ago, when Detective Bohan was investigating rapes and murders, he never  would have dragged himself out of bed near midnight for an overdose. The most attention a drug death received then was a brief visit from a uniformed patrolman to check for foul play, he said. “Until the heroin hit so bad…there was really no investigation afterward.”

Earlier that day, a group of task-force officers attempted to gather evidence against an alleged dealer linked to a different overdose death. In a police station parking lot north of Hamilton County, Lt. Joe Boyatt and his colleagues affixed a hidden wire to an informant who barely survived an overdose after taking drugs from the same alleged dealer. His friend wasn’t as lucky and died from what turned out to be a fatal combination of fentanyl and other synthetic opioids.

Lt. Boyatt, 61, recruited the 26-year-old man to be a confidential informant while he was recovering in the hospital a few months earlier. “We want to find the people who are selling the stuff,” Lt. Boyatt told the young man. “There’s nobody but you that has as much information.”

The informant, a college graduate with dirty-blond hair, said he agreed to cooperate with the police “to bring closure to [the] family” of his friend. “I’m just gonna try to do right by him,” he said.

In a nearby suburban neighborhood, the officers watched from parked cars as the dealer approached the informant’s car and allegedly sold him $60 worth of fentanyl. The investigation is continuing.

The task force presents its cases to either the county prosecutor or the U.S. attorney in Cincinnati, who decide whether to press charges.

On the night of Daniel Eckhardt’s death last year, he was with his ex-wife, Bridget Bode, and her boyfriend, Wesley Dean Williams. Also there was Destany Davidson, who was on a first date with Mr. Eckhardt, according to the task force’s investigative report.  After buying $120 of heroin in Cincinnati, the quartet drove 30 miles back to Mr. Williams’ house in West Harrison, Ind., where they spent the night getting high.

Ms. Davidson, 19, told police that awoke around 4 a.m. to find that Mr. Eckhardt was lying next to her dead from an overdose. After carrying Mr. Eckhardt’s body and possessions into Mr. Williams’ car, the group drove around for a short while, then crossed back into Hamilton County and dumped Mr. Eckhardt’s body on the side of a road, according to the investigative report.

The coroner’s office later found that the heroin Mr. Eckhardt used also contained fentanyl, and he likely slipped into a coma “for some time” before dying.

After the task force completed its investigation, the detectives handed the case to Seth Tieger, a veteran Hamilton County prosecutor, who charged the trio with tampering with evidence, abusing a corpse, corrupting another with drugs and involuntary manslaughter.

Ms. Bode and Ms. Davidson each pleaded guilty to involuntary manslaughter and tampering with evidence, and were sentenced to three years in prison. Mr. Williams pleaded guilty to tampering with evidence and also received a three-year sentence.

The sentences weren’t harsh enough to satisfy Mr. Eckhardt’s mother, Pamela Eckhardt, who says she was blindsided by the plea agreements. “It was a slap in the face,” Ms. Eckhardt says, sitting in her sister’s upholstery shop on Cincinnati’s west side. “It was shoved under the rug like his life didn’t matter.”

Mr. Tieger says sending all three defendants to prison was a good outcome, and that sometimes victims’ families are “looking for more from the justice system than we’re able to give.”

A two-hour drive south from Hamilton County, Kerry B. Harvey, the mustachioed U.S. attorney for eastern Kentucky from 2010 to early 2017, made prosecuting drug-deaths a priority around 2015. He used a 1986 federal law that had rarely been applied in the district, which established a mandatory 20-years-to-life sentence for distributing drugs that resulted in death or serious injury. The penalty grew to life in prison for
defendants with prior felony drug convictions.

He saw the approach as a way to bring solace to families devastated by the increasing number of heroin-related deaths in the area. Plus, the law’s stiff penalties helped persuade dealers to cooperate against bigger suppliers, he said.

“When someone is looking at 20 years to life, they’re gonna tell you whatever they know to save themselves,” he said.

Mr. Harvey assigned three prosecutors to work on the cases and began working with local police to investigate overdose deaths as homicides. Since 2015 one of the prosecutors, Todd Bradbury, has convicted 16 people for selling drugs that resulted in death, two of whom received life sentences. One of those convicted was Fred Rebmann, who in 2016 sold $60 of fentanyl to Kathleen Cassity. Ms. Cassity was six months pregnant and died within hours of buying the drugs. Doctors performed an emergency C-section, but failed to save the life of her unborn child.

At the time, Mr. Rebmann was 31 and spent his days scheming to obtain enough heroin to avoid withdrawal. “I would work odd jobs…steal…hold up signs for money,” he said in an email from prison. He also dealt drugs. “There were days I’d sell heroin to get my own, and there were days I sold scrap metal,” he said in a telephone interview.

Addiction doesn’t “disqualify” small-time dealers like Mr. Rebmann from prosecution, says Mr. Bradbury, the prosecutor. “He knew he was selling something extremely dangerous to a pregnant woman,” he says. Mr. Rebmann says he didn’t know Ms. Cassity was pregnant.

Mr. Bradbury offered him a deal. If Mr. Rebmann pleaded guilty, prosecutors would recommend a 20-year sentence that, with credit for good behavior, could be reduced by three years. If he went to trial and lost, Mr. Rebmann faced mandatory life in prison because of a 2012 heroin-possession conviction.

Mr. Rebmann took the deal and pleaded guilty in August 2016, but U.S. District Judge  Joseph M. Hood, a Vietnam War veteran appointed to the bench in 1990, rejected Mr. Bradbury’s sentencing recommendation. Ms. Cassity died “because you wanted to stick a needle in your arm,” Judge Hood told Mr. Rebmann, according to a transcript of the hearing. He sentenced Mr. Rebmann to 30 years in prison.

“I want it to be known here in Lexington… if you get convicted of dealing in heroin and a death results, 20 years isn’t enough,” Judge Hood said. “Time for coddling is over.”

Published by the Wall Street Journal