Madeline Lanaro, whose daughter Monica Jack was 12-years-old when she was murdered in 1978 near Merritt, B.C., wipes away tears after the RCMP announced an arrest in connection to her murder and that of Kathryn-Mary Herbert, during a news conference in Surrey, B.C., on Monday December 1, 2014.

Image Credit: THE CANADIAN PRESS/Darryl Dyck

VANCOUVER - Shari Greer made a promise to her 11-year-old daughter as she grieved over the girl's grave site that she would never give up the hunt for the killer.

Almost 40 year later, Greer says she's still wrapping her head around an arrest made on Friday that brings resolution to her mission.

Mounties in British Columbia revealed Monday they have arrested and charged a 67-year-old Ontario man with first-degree murder in the historic deaths of two young girls, who separately vanished near their homes in the 1970s.

Kathryn-Mary Herbert, 11, disappeared in Abbotsford, B.C., in 1975, and 12-year-old Monica Jack was last seen in Merritt, B.C., three years later.

"When this is over, I am going to have a well-deserved breakdown. I will forever hear my heart break," Greer, Herbert's mother, told a news conference after police thanked her for her relentless advocacy over the years.

"I want you to know these two little girls, Monica and Kathryn-Mary, made a difference in this world while they were here."

Both girls disappeared while travelling short distances while alone on roads in the southern part of the province.

Officers refused to provide specifics of what led to the breakthrough, saying they brought Garry Handlen into custody without incident in Surrey, B.C., although he no longer lives in the province.

Supt. Ward Lymburner, the officer in charge of the special projects unit, said three decades of investigation by multiple police forces combined to pinpoint the same suspect.

He described Handlen as having travelled extensively through B.C. and Alberta at the time and released the man's photograph from that era, asking the public to come forward with tips if it jogs any memories. He said the man previously lived in the Lower Mainland and has a criminal record.

"He was brought into the investigation as a suspect or person of interest ... early on," Lymburner said.

"It has taken this long for us to gather the evidence needed in order to satisfy the courts to bring him forward on charges today."

He wouldn't comment on any existence of DNA evidence, but said all advances in forensic technology have been brought to bear.

Herbert was reported missing on Sept. 24, 1975, after failing to return home from a friend's house in Abbotsford, B.C., about 8:30 p.m. She was last seen by another friend who doubled her on his bicycle part-way, police said.

The girl's body was turned up two months later in an undeveloped area of a First Nations reserve, prompting a series of investigations that included the issuing of a private $10,000 reward in 2012.

Jack was last spotted on May 6, 1978. She was riding her bicycle alone along a stretch of Highway 5A, near the Nicola Ranch in Merritt, B.C., more than 200 km northeast from where Herbert disappeared.

The girl's bicycle was found strewn down an embankment the following afternoon, not far from where she lived, but it took another 17 years to find her body. Remains were discovered in a rural area north of the city, after a fire.

Investigators added the mystery of Jack's death to Project E-PANA, which had been probing 18 unsolved homicides or missing-women cases along B.C. highways. In 2007, new investigators reviewed 500 previously-conducted police tasks and initiated 241 more tasks, including a series of re-interviews and new forensic analysis.

"Every time I hear news on the TV about some other little girl or boy disappearing, or found murdered, it really hurts me. I know how that feels," said Jack's mother, Madeline Lanaro.

"We expect our parents to die, but we don't expect our children to die."

Handlen remains in custody and is scheduled to next appear in Abbotsford Provincial Court on Dec. 8.

— Note to readers: This is a corrected story. An earlier version mispelled Monica's first name.

News from © The Canadian Press, 2014