DARTMOUTH, N.S. -- Gary Harris knows how he wants his 15-year-old niece, Miya Harris, to be remembered. 

"As the sweetest little girl that she was," he says. "She loved to be with her family. Every time I come down home to come see the family, she always wanted to come spend time with her uncle, go for walks, just anything."

According to her obituary, the Dartmouth High School student was an "enthusiastic" rugby player, and loved spending time with her dog, Lacey.

Harris had made plans to see his niece after he had just finished his two weeks of self-isolation last week, having come from Ontario to visit his sister and family in Dartmouth, N.S.

He intended to spend time with Miya last Wednesday. Instead, he was woken by police in the early-morning hours of June 10.

"We were able to go to the scene where she was at, and we had to follow the ambulance there (to the hospital)," he recalls. "I was at the hospital with my sister when we got the news."

It was 45 minutes later.

When asked if his niece had ever tried any drugs before, Harris says, "absolutely not." But he says, as far as the family knows, Miya died of an overdose.

"It was a 'molly' overdose, that was probably laced with fentanyl, is our guess right now," he said. "It's very scary."

According to Halifax Regional Police, officers did respond to a medical call to an address on Leaman Drive in Dartmouth around 1 a.m. on June 10.

Spokesperson Const. John MacLeod confirmed a 15-year-old girl was taken to hospital, where she died. He says another 15-year-old girl was also found in medical distress in the same area. She was taken to hospital for treatment.

Police can't say yet what was behind the girl's death.

"We're currently investigating as to what occurred that evening," says MacLeod. "We are awaiting results from the Medical Examiner's officer, as well as any association tests that they've done."

Matthew Bonn, of the Canadian Association of People Who Use Drugs, is a drug-harm-reduction advocate who works in education and awareness around safe drug use.

"A lot of the time, people who are using drugs, or 'molly' specifically, are people that are younger, youth, it's people who are experimenting," Bonn said.

He's concerned to hear the drug may have been laced with fentanyl, because 'molly' is often used by young people.

The drug is a powerful stimulant -- also known as MDMA -- with psychoactive effects. He says he has witnessed overdoses caused by 'molly.' 

He says families and communities need to have an open conversation about street drugs in Halifax.

"We know young people are going to experiment with drugs," he says, "so we have to look at it, OK, how can we make sure that they're going to do it safely? Can my child talk to me openly about drug use?"

Gary Harris says he has spoken about his family's loss, to try to prevent such tragedy from happening to others. 

"Stay right on them with that lecture on drugs," he says. "As much as they don't want to hear it, as much as they are, like, 'mom, dad, that's enough,' drill them into it more. We can't be losing kids the way that we are."

A small private funeral will be held for Miya Harris on Tuesday.