Tuesday, marked 50 years since a West Michigan teenager went missing in Allegan County.
Decades later, family and friends hope someone out there knows what happened to Kathy Sue Wilcox.
Karen Wilcox said she spent years blaming herself. Police initially had listed Kathy as a runaway after a situation happened at their home.
Wilcox hopes that hearing this story can help end this cold case.
"It feels like I don't remember what our voice sounds like anymore. And sometimes that bothers me that I don't even remember what our voice sounds like," Wilcox told FOX 17.
Kathy Wilcox was a small-town girl from Otsego.
"She was light-hearted. She was brave and courageous. She really didn't seem like she was afraid of anything," Wilcox said.
Half a century later, her sister hopes someone can help solve this case.
"There may be the great hope that there's one person who will be going to bed tonight thinking 'I need to tell somebody when I know. I need to tell somebody, what I know. I need this family to have all this information. I need to tell them,'" Karen said.
Many in Otsego feel the same way.
"You just gotta keep hoping somebody's out there that knows something. And maybe a clue comes up. You just don't know when that's gonna happen. I don't believe you can give up," childhood classmate and friend Ronnie Marks said.
On July 12, 1972, Kathy, just 15 at the time, had an argument with her stepmother over boys.
Karen says she doesn't remember what was going on, but remembers she was the one who told her stepmother.
"I guess, Kathy's face got slapped or something. You know, she came stomping out on steps, and you know, she said, 'I will never tell you anything again. To you. Right?' She said that to me. And then that was it. You know, I never saw her after that," she added.
The once 5'4, 130 pounds brown-haired, blue-eyed girl would look much different. She would now be in her 60s today.
Karen says it was a few years ago she was able to come to peace.
She says while on a spiritual trip with a friend, she's come to accept she may never see her sister again.
"I mean, I've accepted, I firmly believe, you know, that she's gone from us," she said.
Though she and others who knew Kathy, still hold out for answers.
"It would be nice to have a closure story. However, it comes out." Marks said.
