Oswego County District Attorney Greg Oakes said he occasionally goes by the former D&W convenience store in New Haven where Heidi Allen was last seen on April 3, 1994.

"Every time I see it, my chest tightens up a little bit,” he said.

It’s probably a similar feeling for anyone who grew up near the store, which is now a Valero gas station. But Allen’s sister, Lisa Buske, said she also has another feeling when thinking about Heidi.

"Hope is what makes it possible to put my feet on the floor and face each day,” Buske said.

She and her family have been hanging on to hope for the last 25 years.

"Without hope, I would probably just lie in bed and not do anything,” she said.

Allen worked at the store as a cashier when she went missing on Easter Sunday years ago. Gary Thibodeau would later be convicted of kidnapping her and died in prison after multiple attempts at a new trial.

But the investigation never found out what exactly happened to Allen.

"The DA has his own ring tone, the sheriff has his own ring tone and the sheriff has his own ring tone,” Buske said of how her phone is programmed. “So for 25 years, you don’t know what they're calling for. There's stuff that happens that nobody knows about. A body might have been found five states over with similar characteristics. We get the phone call they are comparing DNA.”

The mystery of Heidi Allen now spans multiple decades, leaving Buske only with memories of her sister. Now a teaching assistant, she has found ways over the years to cope with growing up alone.

She runs a "Where's Heidi?" Facebook page and podcast. She has also written a book.

"Just some of the things that siblings feel when they lose a sibling, because it’s different than a parent or grandparents,” Buske said of her work. “It’s different and there wasn't anything out there. So someone said, ‘so write it.’”

From trials and appeals, to a brother's death, and a sister still wondering what her sibling would have become, no one's life will ever go back to the way it was 25 years ago.

"I didn’t dare go anywhere by myself because I was thinking they are going to try to arrest me for something else I didn't do,” said Richard Thibodeau, Gary’s brother. He was also arrested and put on trial in the Allen case but was acquitted of all charges.

Then there’s Gary Thibodeau, who for 23 years maintained his innocence from prison, and whose role in the case and investigation is forever removed after he died last August.

“Do we have an innocent man who spent all of the remainder of his last 22 years in prison for something he did not do?” said Lisa Peebles, Thibodeau’s former public defender.

Allen’s family and law enforcement officials wonder, after so many years, whether there will ever be real closure.

"We would’ve hoped and would’ve thought someone would’ve seen something that morning,” Oakes said.

Buske said if Allen were alive today, she “would probably be doing something along the line of social services.”

That's just the type of person Heidi was — putting others first — even that Easter morning in 1994, when she went into work for a co-worker who wanted to spend the holiday with family.

"I have relatives, they count the days. They can tell you how many days, every day,” Buske said. “I used to, but I can't. It’s just not healthy for me. It’s just more in the public spotlight. We appreciate that because, you know, this may be the interview where someone says ‘I know. I know where she is.’”