There are moments that can haunt us, seconds that stay with us forever, words spoken that then replay year after year.
And that's how the evening of July 17, 1972 is for Karen Wilcox. That was the night her sister Kathy Sue walked out of the house, never to return.
43 years later, Karen, who was just 16 at the time, remembers she was sitting outside her Otsego, Michigan home on the porch swing. Inside, she heard her younger sister Kathy Sue engaged in a heated argument with their stepmother.
Arguments were common in the Wilcox childhood home. Their parents had divorced and their father remarried. Karen described the family dynamic as "dysfunctional." Kathy Sue, however, usually stayed out of the tumult.
But that night was different.
"Kathy Sue never got into those kinds of arguments with our stepmother," Karen Wilcox told Dateline NBC. The fight, apparently, was over their stepmother's disapproval of Kathy Sue's new boyfriend. The teen stormed out of the house.
"When she walked away that night, she said 'I'll never talk to you again.'"
She left with just the clothing on her back, a simple purple T-shirt and jeans.
That July evening was the last time anyone saw or heard from Kathy Sue. She was 15 years old.
According to police, community members reported seeing her later that evening and the following day, but detectives have found no sign of her since.
For Karen, time has not healed the pain of losing her only sister.
"Everybody loved Kathy," Karen remembers. "She was brave, she was adventurous."
In the early 1970s, standards for missing persons were much different than they are today. Although the Wilcox family conducted their own search effort for Kathy Sue, they were reportedly told they must wait 72 hours to report her missing.
"1972 was way before any of what we know is customary today," said Karen Wilcox. "It was before Amber Alerts and everything we have available for families now."
As that summer came to a close and kids headed back to school, Kathy Sue's case quickly went cold.
Karen says her sister's case was open for just two months.
Many at the time believed Kathy Sue had run away. Even to teenage Karen, growing up in a family riddled with frequent arguments and stresses, she thought Kathy had perhaps chosen to escape.
"She was considered a runaway. It seemed plausible," said Karen. "But lately, I don't believe she ran away. I think about how loved she was. I believe there is someone in that town who knows something."
A Perfect Stranger
Karen has since moved away from Otsego. She married in 1976, and now works as a counselor in Billings, Montana.
With the rise of the internet, Karen felt new-found hope that her sister was out there somewhere and she could find her. She would consistently type Kathy Sue's name into search engines hoping for some type of hit.
Then, in 2011, Karen came across a comment mentioning Kathy Sue on Facebook from a woman named Shannon Froeber, a stranger to Karen at the time.
"Otsego is such a small town, everybody knows everybody," Shannon told Dateline NBC. "So I couldn't figure out how I didn't know about this missing girl, and nobody else did either."
A lifelong resident of Otsego, Froeber had stumbled across the Kathy Sue case online. She was captivated enough by the young girl's story and photograph that she decided to dedicate herself to spreading awareness about the case in the local community.
With Karen's permission, Shannon established a "Find Kathy Wilcox" Facebook page. A community more than a thousand strong has since formed and continues to grow. Others have now jumped in to lend themselves to the cause.
The renewed interest has brought hope to Karen and Shannon, who have become allied in their wish to someday find Kathy Sue.
The Unending Search
The detective currently assigned to the Kathy Sue's case is Bruce Beckman of the Otsego Police Department.
"She is the only cold case for Otsego," Detective Beckman told Dateline NBC. "I would hope if she is alive, she would contact somebody. And if she isn't, I would hope that we can find whatever is there."
According to Beckman, DNA obtained from members of the Wilcox family allowed Kathy Sue's case to be added to the Missing Persons of America system. That DNA can be tested against unidentified remains that are discovered.
But until then, or until an Kathy Sue is found alive, police say there isn't much more that can be done.
Karen is not quiet about her unhappiness with the investigation into her sister's disappearance. Several posts online question the actions police took all those years ago. Whatever occurred in the initial search, Karen still yearns for the investigation into her little sister's case to move forward.
"I am not going to leave any leaves unturned when it comes to finding her," said Karen. "And I know that I might not find her alive. I know that today. I know that's a possibility."
Anyone with information about Kathy Sue Wilcox is encouraged to call the Otsego Police Department at (269) 692-6111.