Colorado girl's remains found after 35 years — now family seeks killer
Jonelle Matthews is seen in this photo distributed after she disappeared Dec. 20, 1984 at the age of 12.

via KDVR

GREELEY, Colo. (KDVR) -- For nearly 35 years, Jonelle Matthews’ family could only wonder what had happened to the 12-year-old girl whose disappearance attracted the attention of the White House and shocked Greeley.

They have faced false alarms over the years whenever human remains were found or police interviewed someone new for information about Jonelle.

In July, they finally learned what happened to their daughter and sister — a construction crew discovered her remains, and police officially labeled her death a homicide.

But they still don’t know who killed her. Finding her body ended one chapter of the family’s life and opened another, said Jennifer Mogensen, Jonelle’s older sister.

“Somebody is responsible for doing this to her,” Mogensen said this week.

After singing in a holiday concert at her middle school on Dec. 20, 1984, Jonelle was taken home by a friend and the friend’s father.

She was last seen at 8 p.m., entering the ranch-style home where she lived with her father, Jim; mother, Gloria; and sister.

Their father arrived home from Jennifer’s basketball game about an hour after Jonelle but found an empty house, The Greeley Tribune reported.

Their mother had left earlier that day to visit family in another state, Mogensen said.

Despite an intense search that started that night, no one was ever arrested.

Jonelle’s disappearance was among the cases highlighted by then-President Ronald Reagan as his administration launched a national effort to find missing children.

MORE: Greeley girl’s remains found after 35 years — now family seeks killer - KDVR