A police social media campaign launched to generate leads on cold cases in central Ontario bore fruit this week as a man was charged with first-degree murder in the deaths of two men who vanished in 1991, investigators said Wednesday.

Ontario Provincial Police and the Barrie Police Service said Michael Guido Gerald Claes, of Elmvale, Ont., was charged Monday in the deaths of Grant Ayerst and Norman Whalley, and remains in custody.

The two men, aged 21 and 36 respectively, were last seen leaving a hotel in Toronto on Sept. 11, 1991. Their remains have not been found.

Police did not specify exactly what evidence led to the arrest of 49-year-old Claes, who they said grew up in Barrie, Ont., and was known to them for several years.

But Det.-Insp. Gilles Depratto, the major case manager on the file, said in an interview that police wouldn't have been able to make an arrest without information gleaned from the public in the wake of the social media campaign launched last year.

"We can't say specifically if one tip helped us come to the successful resolution, but we can say there was a lot of discussion in the public and there was a lot of people who provided us information," he said.

While the case is before the courts and there's a long road ahead -- complicated by the fact that the bodies of Ayerst and Whalley have not been found -- Depratto said he's confident the case will come to a successful conclusion.

He noted that it was satisfying to be able to tell the families of Ayerst and Whalley that investigators believe they've arrested the alleged killer.

"It's the most important thing, because what we work for in homicides is to be able to bring some resolution in the family," Depratto said.

"They didn't want to be disappointed again," he added. "That was one main thing, that they've seen the investigation move forward at different times in the last 26 years, and they didn't want to be disappointed."

The Ayerst family issued a written statement that thanked police for their efforts.

"Early on in this tragedy we chose not to let the events surrounding Grant's disappearance destroy our lives," the family said. "Instead we chose to keep the good memories alive, hope to move us forward and always anticipated the day we would have some resolution to this tragedy which disrupted our lives over 26 years ago."

"Patience, karma and hope have paid off," the family added.

The disappearances of Ayerst and Whalley were among four cold cases profiled by the provincial and Barrie police forces last year as part of a project called the Simcoe County Case Files, prompting renewed interest and offering hope to the families of the alleged victims.

As part of the project, police created a Facebook page where they profiled the cases in episodic videos that have now been viewed hundreds of thousands of times.

They also wrapped a cube van with case information to direct viewers to the Facebook page and encourage tips. The van was strategically parked in various locations throughout the Greater Simcoe County area.

The series of videos explains that Ayerst and Whalley arrived in Ontario from British Columbia in September 1991 "to carry out an illicit drug transaction," and were never heard from again.

The other cases part of the project included 17-year-old Cindy Halliday of Waverly, Ont., who was last seen hitchhiking near Midhurst, Ont., in 1992. Her remains were discovered months later, and questions still swirl around what happened to her.

April Dobson, 40, was sitting on a friend's porch in 2005 when she was shot to death, and the body of 30-year-old Jaimee Lee Miller was found in a wooded area in March 2016, five months after she was last seen.

All of the cases included in the project are believed to be homicides.