The last time Jonelle Matthews was seen by anyone who knew her, the 12-year-old girl was entering her own home, having just finished singing in a Christmas concert at a retirement home.
She was dropped off by her friend Deanna Ross, and her father Russell Ross. Both watched to make sure Jonelle got in the door. It was five days before Christmas in 1984 in Greeley, Colorado.
She took off her shoes and turned on the TV, investigators would later say. Her dad was at her sister's basketball game. Her mom had gone to visit family for the holidays. Jonelle moved a space heater into the living room. There was snow on the ground.
When her father, Jim, and her 16-year-old sister, Jennifer, got home at 9:30 p.m., Jonelle was gone. She was never seen again.
On Thursday, authorities announced that construction workers digging a pipeline had stumbled upon human remains. An autopsy concluded they belonged to Jonelle.
"It's still kind of surreal," said her sister, Jennifer Mogensen. "It's closure for me and my family, but also raises new questions now. It's sad. We're sad," she told KUSA-TV.
No arrests were ever made in connection with Jonelle's disappearance. Her story drew nationwide attention as hundreds searched around her suburban home. President Ronald Reagan pleaded for help in finding her. Jonelle "would have celebrated a happy 13th birthday with her family just last month," he said after she vanished. "But five days before Christmas, Jonelle disappeared from her home."
His administration helped open a toll-free hotline for missing kids. The president urged members of the National Newspaper Association to publish photos of the country's missing children as a "mission of mercy."
Three years later, Adam Walsh vanished from a Florida shopping mall. The highly publicized case pushed his father, John Walsh, into becoming an outspoken advocate for abducted children. John Walsh went on to host the show "America's Most Wanted."
Jonelle's strange disappearance riveted her hometown for decades. Authorities were, and remain, tight-lipped about the baffling case, saying they needed to keep certain details private to ensure the right suspect was caught.
Jonelle was in seventh grade when she vanished. She sang in the honor choir and was active in her church. Jennifer described her little sister, who had thick wavy hair and new braces, as a "strong, independent, opinionated 12-year-old.
"She knew what she wanted and how things should be done," she told The Associated Press Thursday.
Her parents, who retired to Costa Rica, will travel to Greeley to claim their daughter's remains, she said. "They're sad. They're grateful for all the hard work the Greeley Police Department has done."
Weld County Sheriff Steve Reams said investigators were treating the case as a homicide investigation. A cause of death was not immediately disclosed.