Early Saturday morning, Nathan Dvorkin came home from a birthday party in Queens, brushed his teeth, and went to say goodnight to his little brother.

When he opened the translucent doors of the living room, he found 15-year-old Lewis Dvorkin lying, mouth open, on the white and tan striped sofa, with the Music Choice Channel playing in the background. Nathan, who is 17, thought Lewis was sleeping there, in front of the television. When a slap to the cheek got no reaction, Nathan screamed for his mother.

That scene, ending with Lewis dead of a heroin overdose and the family “devastated” and “numb,” was the final act in a three-year struggle to help Lewis, a sophomore at the elite Bronx High School of Science, redirect his life.

“I’ve tried so hard for the past few years to get Lewis help, and everywhere I went I just came to this dead end,” the boys’ mother, Carole Robinson, said yesterday, sitting in a high back yellow chair in their cozy East 86th Street apartment.

“I think kids have got to realize just how dangerous these situations are, and they have to come forward, even if they do that anonymously,” she said. “And then adults have to help you learn this, do something about it, and not just be angry or just think, ‘It’s not my child. It doesn’t matter. It’s not my business.’ I think we have to become my brother’s keeper.”

In a 90-minute interview yesterday, Ms. Robinson and Nathan, a senior at the Urban Academy, sat in the same room where Lewis lay dying just six days before. The room, where one of Lewis’s three beloved guitars rests behind a second sofa, overlooks 86th Street and shares a wall with Lewis’s bedroom. There, a huge stuffed brown bear still slumbers on his loft bed and history and math textbooks line the bookcase.

Ms. Robinson said she wanted to talk about her younger son’s death because she wants Bronx Science to seize this moment to tackle its drug problem. She said she wants other children to seek out help before it’s too late, and she said she wants other New York City parents to do all they can to prevent drugs from killing their sons and daughters.

His mother first suspected Lewis had a problem when he was in middle school. He had left the warm shelter of P.S. 6, where the principal, Carmen Farina, now the deputy schools chancellor for teaching and learning, knew all the children and came outside to greet them every morning. East Side Middle School had been “fabulous” for Nathan, but for Lewis it was isolating.

He wasn’t doing any work, and Ms. Robinson sent him in for a long, exhausting series of assessments for emotional and learning problems. Lewis didn’t have a learning disability, and a therapist assured her that he wasn’t using drugs. Another therapist said Lewis’s problems weren’t “serious enough” to warrant the care he could offer.

When Lewis was admitted to Bronx Science, which is one of the specialized public high schools that require an entrance exam, a friend phoned Ms. Robinson and warned her that drugs were rampant at the school. She phoned the therapist who had worked with Lewis years before, when she and her husband divorced, and talked about the school’s reputation. She also talked to Lewis.

“It was a concern,” she said. “It was something I was aware of, but at some point you have to trust your kids, and you have to trust the people you send them to be with at school.”

At the start of ninth grade, she said, Lewis told her about how students would skip classes and walk to the grassy hill across the street from school to do drugs. At first, Lewis told her he wanted to switch to a new school, but then he decided to stay.

Ms. Robinson said she knows now that he was doing drugs – serious, dangerous drugs – but she said he was acting normal.

But then again, she said Lewis convinced her that he used spray paint only to decorate the desk and chair in his bedroom, when he was actually scrawling the initials “MT,” which stand for a childhood nickname, Motard, all over the Upper East Side. Wednesday night, a friend shaved the tag into the left side of Nathan’s head, as a sort of memorial.

She said Lewis and his Bronx Science friends covered up for each other when it came to drugs. And apparently, she said, the school did nothing to stop their destructive behavior.

“They have responsibility to admit that they have this problem,” Ms. Robinson said. “They know the kids go over to this hill to do drugs, so why is the hill still there? Why are they allowed to go over there?”

She continued: “Kids need to know what to do in these situations, because it’s obviously happening. We give out condoms and free syringes. But we don’t give out instructions on what to do in emergencies to kids or even, I hate to say it, but if a kid’s taking heroin they should know the safety things about it. If we can tell them how to put a condom on, surely we can tell them the real dangers of some of those terrible drugs, not just that it could kill you.”

Nathan, who was quiet for most of the interview, said he doesn’t know if keeping students in the school and off the hill would help keep them away from drugs. What might really help, he said, is a meeting place for Upper East Side teenagers to replace a now-closed skate shop, Blades, that was a safe, secure hangout for children. He’s looking into creating such a place.

As for Bronx Science, he said the administrators should admit what’s going on in the school’s hallways and across the street.

He said it seems as though Bronx Science’s principal “wants to keep up the reputation.”

“You want to send your kids to a school where you don’t think there is a drug problem,” he said, “and I think she’s doing a pretty good job, because I don’t know of any people who really think of Bronx Science as a failing school.”

The principal, Valerie Reidy, has not returned telephone calls requesting comment.

What Nathan Dvorkin said intuitively was right on track, according to John Sheehan, vice president of the drug treatment center Phoenix House.

Unless people come out and talk about what happened, as Nathan and his mother have done, people are unlikely to learn from Lewis’s example, Mr. Sheehan said. He said Lewis’s classmates, who already do drugs, would probably turn to drugs to relieve their stress. And he said that if the school doesn’t confront the drug issue head-on, history would quite likely repeat itself.

“Sometimes institutions, when confronted with tragedy, want to see the tragedy as an isolated situation. … You would hope that this is a wake-up call and something should be done, and I would hope the Department of Education, who I know is committed to working with kids with drug problems, would help the principal and the school staff there and put a major effort into it,” Mr. Sheehan said.

“It’s not that people can’t learn, but people have to seize on it to learn from it,” he continued. “To really make change you have to be motivated and organized.”