Monique Sellis inside her home in Jericho, Wednesday, speaking about...

Monique Sellis inside her home in Jericho, Wednesday, speaking about her son, who died of a heroin overdose. Credit: Newsday/Steve Pfost

A Nassau County drug dealer was convicted Tuesday of distributing the heroin that caused the 2018 overdose death of a fellow drug addict he met at a rehab in Mineola, according to the U.S. Attorney's Office.

The dealer, James Tunstall, 48, of Freeport and Westbury, now faces up to life imprisonment, following Tuesday’s jury verdict finding him responsible for the Oct. 29, 2018, death of 24-year-old Sergio Niko Alvarez of Jericho, according to a news release from the U.S. Attorney’s Office for the Eastern District of New York, which covers Long Island.

Sentencing is scheduled for April 20, according to court records.

Tunstall’s trial, which lasted five days, was before U.S. District Judge Joan Azrack at the federal courthouse in Central Islip.

Tunstall — the father of four adult daughters and a son, according to his attorney — had already pleaded guilty in July 2021 to his role in a conspiracy to distribute cocaine and heroin and had been sentenced in December 2022 to 20 years in prison.

The defense attorney, Peter Brill of Hauppauge, who was appointed by the court, declined to comment Tuesday evening.

Alvarez's mom, Monique Sellis, 52, a registered nurse in Jericho, who attended the trial, said the roots of her son’s addiction to opioids date to when he was a teenager and he suffered an injury while playing baseball as a center.

Monique Sellis with her son Sergio Niko Alvarez in a...

Monique Sellis with her son Sergio Niko Alvarez in a family photo. Niko Alvarez died of a heroin overdose at age 24. Credit: /Family photo

“He’d been struggling with addiction for a good five years prior to him dying. Started out with, probably he had a taste of OxyContin when he broke his wrist when he was 16 years old,” she said in an interview.

In opening arguments, Brill had argued that there couldn’t have been enough heroin to kill Alvarez because a third addict also in rehab — Tunstall’s co-defendant, Jay Tenem of Syosset, Tunstall’s deliveryman who went on to be a government witness — “broke off a piece” of the drugs for himself, and so given the limited amount of drugs alleged to have been sold, there would be an insufficient amount left over.

The government saw it differently.

“Tenem collected the victim’s payment for the heroin, and brought the cash back to Tunstall. The victim was found dead of heroin intoxication the next morning in his bedroom, by his mother. The evidence included text messages between the defendant and the victim, and between Tenem and the victim,” the U.S. Attorney’s Office wrote in the release.

In one of those exchanges, Tunstall negotiates prices for the drugs with the victim, and texted, “I don’t do this for fun,” the release said.

Tenem, who testified at Tunstall’s trial, pleaded guilty in February 2019 to distributing the heroin that caused Alvarez’s death and is awaiting sentencing.

Newsday reported last week that Tenem cooperated with government investigators since his arrest on the day of Alvarez’s death and served 34 months in the county jail before he pleaded guilty to both counts in the indictment against him and Tunstall. Tenem has said he hopes that because of his cooperation and his ability to remain sober he will ultimately be sentenced to jail time served.

Across the country, the number of so-called drug-induced homicide prosecutions has gone up, according to a 2017 report by the Drug Policy Alliance. Using media mentions as a gauge, the group found that in 2011, there were 363 news articles about such prosecutions. By 2016, the number had gone up to 1,178.

The drug Alvarez first started using wasn't illegal. That opioid was prescribed for the baseball injury. 

And then, he cut his cast off to play in an all-star game, and “I remember him saying … 'oh my God, I need pain medicine because it hurts so much,' and I remember him having leftovers and going back to it, and me not really thinking anything of it, looking at it more, even as a nurse, as like a Tylenol, because it’s prescribed by a physician, no stronger than a Motrin, not really understanding what that really was, at the time.”

He soon graduated from Jericho High School, with an academic scholarship to the University of Tampa, and by then had gotten into marijuana, Xanax and alcohol, and later cocaine.

He was arrested several times for driving while intoxicated, and at one point suspended from college for a fight, and didn’t go back due to his drug addiction. Over the next several years, he was in and out of rehab — “he was really trying,” Sellis said — and criminal court.

“He wasn’t your typical addict, strung out,” she said, describing how the day before his death he played softball, hitting a home run, and went to the gym to work out.

But having taken the heroin that came from Tunstall, Alvarez died in his mother’s house, in his bedroom. Photos of him, his grandmother and other family were nearby.

“I found him. I performed CPR on him. I found him in the morning but he had already died,” she said, adding: “It was heart-wrenching. It was the worst thing that can ever happen to anybody.”

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