A week later, Shari Greer received an anonymous donation of $10,000 to help move the cold case forward.
Greer said she is now offering the reward for information that will lead to the arrest and conviction of the person or persons who killed her daughter, Kathyrn-Mary Herbert.
"Someone knows what happened and who did this to her," Greer said during a Thursday news conference. "I hope with the passage of time this person will come forward and call the police with any information they may have."
The partially decomposed body of Herbert was found Nov. 17, 1975, on the Matsqui First Nations reserve, in British Columbia's Fraser Valley, about 80 kilometres east of Vancouver.
The young girl, described by her mother as a child who loved to sing and could play piano by ear, was last seen Sept. 24, 1975.
She had been visiting the home of a friend in Abbotsford, B.C., and was walking down a rural road when a friend offered to give her a ride on a bicycle.
RCMP Insp. Gary Shinkaruk said Herbert accepted the ride, and the friends parted ways at an intersection at about 8:50 p.m.
"Kathyrn-Mary never arrived home, and this was the last-known sighting of her," Shinkaruk.
Witnesses interviewed during the investigation recalled seeing a white, older-model, American-made vehicle driven by a lone male and parked between where Herbert was last seen and her home, said Shinkaruk.
He said the occupant of the vehicle has never been positively identified, and police believe he may have information that can help the case.
"We still have persons of interest," he said. "But to date we do not have sufficient evidence against anybody to lay a charge or bring somebody to justice."
Shinkaruk said there are some similarities between the disappearance of two other girls in the area, but police have not been able to definitively connect all three cases.
Shinkaruk said police have cracked historic homicides in the past thanks to advancement in technology, such as DNA, and the deterioration of relationships between killers and their friends.
Whatever the reason, whether its maturity or revenge, individuals who have information should talk to police, he said.
Greer has never lost hope that police will find her daughter's killer, and said she relies on her faith in God to carry her through the tragedy.
She thinks about her daughter every day, one of three children she has buried, and frequently deals with grief, Greer said.
"It's always there," said Greer. "It's always present. There is no such thing as closure, only resolution."