The way Sean Moran remembers it, his best friend was begging for it. And he knew his friend was going to get it somewhere.

So Moran gave him what he wanted: heroin. And with that, his friend overdosed and died.

“No matter what, someone’s going to sell it to them,” Moran said.

Should Moran have been charged with killing his friend? Some in law enforcement, including the head of the Massachusetts State Police, think so.

Last month, Colonel Timothy P. Alben tweeted that charging heroin dealers with murder or manslaughter should be part of the “strategy to attack (the) problem” of opiate abuse in a state that lost 978 people to overdoses in 2013—nearly three times the number who died in 2000.

Massachusetts has it worse than the nation as a whole. The state’s overdose rate in 2013 was double the national average of 7.7 deaths per 100,000 to heroin and prescription narcotics.

Charging dealers when their customers die is not a new idea. But is it a good idea? And does it work?

“It’s not a matter of whether it’s a good thing to do. Everyone wants to do it,” said Berkshire County District Attorney David F. Capeless. “But these are extremely difficult cases to develop evidence in that would result in a viable prosecution.”

There are many reasons why. Capeless said in his county—which had 16.2 overdoses for every 100,000 people in 2013—every overdose death is fully investigated with an eye toward charging someone. But it doesn’t happen often.

“Obviously, the most important witness is deceased,” Capeless said. “And other witnesses who might be of help are typically not helpful. You’re talking about people who are addicted and they don’t want to turn in their dealer very often.”

“You have instances where a best friend can be lost,” he continued, “yet that person won’t cooperate because they’re all thinking about their own survival.”

Capeless got his first manslaughter conviction against a drug dealer in 2009, when a North Adams woman was found guilty and sentenced to three to six years in prison after selling 10 patches of fentanyl, a synthetic opioid, to a woman who later died.

Other counties have gotten convictions for drug providers. Christine Callahan was a jail guard at the Norfolk County House of Corrections in 2002 when she gave heroin to an inmate who died. She later pleaded guilty to manslaughter and served 15 months.

In 2002, a Walpole heroin dealer pleaded guilty to involuntary manslaughter in the overdose death of a friend and was given a three-year sentence in Norfolk County.

Prosecuting these cases is an “uphill battle,” said Jake Wark, spokesman for the Suffolk County District Attorney’s office.

“Ultimately, as sad and tragic as it may be,” he said, “drug use is a voluntary act in almost every case we see.”

There are lots of players between the manufacture of the drug and the ingestion by the user, said Rosanna Cavallaro, a Suffolk University School of Law professor. Charging the dealer is “almost like saying we’re going to prosecute a gun manufacturer.”

“Someone else intervened and used it under their own free will and choice,” she said.

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And there’s another wrinkle: some dealers are addicts themselves.

Joanne Peterson founded Learn to Cope in 2004 after desperately trying to find help for her son, who she said was an addict. The organization now has chapters across the state to help families whose loved ones are battling addiction.

She says some dealers are addicted to drugs, too, just like their customers.

“I don’t think it’s going to solve the problem to arrest everybody,” she said. “What’s going to solve the problem is treatment availability, insurance companies covering treatments where someone needs it.”

“It would cost us a lot less to help them with their addiction before they become dealers,” she said.

The source of the problem includes the pharmaceutical companies that produce powerful pills like Oxycodone, which when misused becomes a gateway to harder opiates for some addicts. And the pipeline includes traffickers who bring heroin over the borders.

Moran, 28 and clean for six months, said there’s an endless number of dealers waiting to supply addicts.

“Someone’s going to sell it if there’s a need,” he said.

Moran’s girlfriend, Mellissa Lavallee, has been clean eight years and relies on methadone to stay that way. The 27-year-old from South Boston thinks it’s a good idea to prosecute dealers, though it’ll be up to addicts themselves to stop the demand for drugs.

“It’s like a variety store selling cigarettes,” she said. “They’re always going to be around.”

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So far this year, state police detectives have handled 22 homicides across the Commonwealth, not including Boston, Worcester and Springfield, which investigate their own deaths.

State troopers have been called on 10 times as many suspected heroin overdoses as homicides– 238.

Alben declined to talk to Boston.com about his tweet. But in an interview with WBUR, he called heroin a “poison,” while also acknowledging the difficulty of linking dealers to deaths.

“Just because it’s difficult or it’s challenging doesn’t mean we shouldn’t do it,” Alben said.

Other states have pursued charges against dealers after overdoses, including Ohio, New Jersey, and Iowa.

New Jersey has trained investigators on how to investigate overdose deaths under the state’s “Strict Liability in Drug-Induced Deaths” statute that was enacted in 1986 as a response to the crack epidemic.

State law in Massachusetts makes it slightly more difficult to hold dealers accountable. Investigators need to prove “wanton and reckless” action, not just negligence.

Prosecutors would have to prove that the dealer knowingly had a potent batch, or had other customers overdose, yet sold anyway, said Wark, the Suffolk County spokesman.

“The person who provided the heroin would need to recognize that there is a foreseeable likelihood that the user would overdose and die as a result,” he said. “They would need to recognize there was a serious risk to life.”

In such a case, peddling especially dangerous drugs would be like reckless driving said Cavallaro, the law professor.

“Those drug dealers are putting people at a different, higher level of risk,” she said.

Dealers can also face charges federally. The cocaine-related death of Boston Celtics draft pick Len Bias in 1986 prompted the federal government to pass a law that levied stiff penalties on drug dealers whose sales can be directly tied to overdoses—a minimum of 20 years, and up to life in prison. The law has been occasionally used in Massachusetts. Other states, like Oregon, federal authorities have charged dealers dozens of times.

But just like their state counterparts, federal prosecutors have the same challenges in gathering the evidence for a successful prosecution: the main witness is dead and connecting the links back to the big distributor isn’t easy. And the U.S. Supreme Court last year further raised the bar by ruling that the drug in question can’t just have contributed to the user’s death (such as in a cocktail of other drugs). It needs to have actually caused the death.

As a dealer, there’s a way to be somewhat responsible about the poison you’re peddling, said one man now in recovery, who spoke to Boston.com on condition of anonymity.

He said and his roommate would get heroin in bulk and test it before cutting and distributing it. That way, they knew how potent it was.

But many users don’t want a weak batch.

”It’s sick,” he said. “But when people are overdosing, they want to try it.”