It has been 50 years since two-year-old Diane Prévost disappeared without a trace but her family still believes she’s out there.

It’s been decades since the day her sister went missing but Lise Nastuk still remembers Sept. 17, 1966 vividly.

Her family was stretching out the final days of summer with a camping trip in Grundy Lake Provincial Park, about an hour away from Sudbury, Ont. Nastuk recalls playing on the beach with her mom, sister and Diane.

”Diane wanted to go to the campsite because she was terrified of the water and she didn’t want to be near the water anymore so she wanted to see my grandparents at the campsite,” Nastuk told CTV News Channel.

Her dad was busy untangling a fishing line and told the impatient toddler to wait “just a minute.”

“Then he turned around and she was gone,” Nastuk said.

Her family combed through the wilderness and checked the campsite but Diane was nowhere to be found.

In 2008, Nastuk revamped the search with a website for her sister. It includes media clippings, photos and a sketch of what Diane may look like today. Since its launch, Nastuk says 10 people have come forward saying they believe they could be her long-lost sister. Each time, Nastuk has directed them to the police to have their DNA tested.

There have been no matches but Nastuk and her family are still hopeful they will find their “petite Diane.”

“It’s like a hole in our family because you know we’re pretty close for four siblings,” she said. “It’s just that we’re missing a piece of our family”

Natsuk says the hardest part for her family is not knowing what happened to Diane – a question that their father never had answered. Bernard Prévost passed away in 2015.

“He never gave up,” Nastuk said.

“I think she is out there, like I really, deep in my heart, believe that she’s living and I’m hoping she had a good life, that she’s with a good family,” Nastuk said.

-          With a report from CTV Northern Ontario