Police say the disappearances of four seniors in the Muskoka area in the 1990s are now being investigated as homicides.

In an update on Thursday morning, Ontario Provincial Police said despite the fact that no bodies have been recovered, investigators now believe Joan Lawrence, John Semple, John Crofts, and Ralph Grant were victims of foul play.

The victims, who ranged in age from 72 to 91, disappeared between 1997 and 1999.

During Thursday’s news conference, police said the seniors had lived at one of three retirement properties owned and operated by four siblings in the Muskoka region in the late 1990s.

According to police, the properties, which consisted of two retirement homes and a farm, housed vulnerable elderly people who were no longer in contact with their families.

During the course of their investigation, Det.-Insp. Rob Matthews said they discovered that some elderly residents would escape from the properties “in the middle of the night” and head to shelters in the Toronto area.

He said police received calls from shelter administrators in Toronto who had concerns about the care people were receiving in the three homes.

“Several charges were laid against individuals involved in the operation of these homes in 2002. Those charges resulted in successful prosecutions concluded through due process in court,” Matthews said.

Matthews did not confirm what charges were laid.

He said the former owners of the properties “have never cooperated with police.”

Police have released few details about the final days of the victims’ lives but Matthews told reporters Thursday that he was in contact with Joan Lawrence just two months before investigators believe she died.

Matthews said while investigating a fraud on behalf of Lawrence, he discovered that she lived in a garden shed on the farm property.

He said the shed did not have a washroom, running water, or insulation, and the only heat source she had was a space heater. He said there were "too many cats to count" also living inside the shed.

Matthews said Lawrence was charged $600 a month in rent and lived in the shed for two years, where she endured “two Muskoka winters.”

While speaking with Lawrence, Matthews said the owners of the property arrived and he questioned them about Lawrence’s living conditions.

Two days later, police returned to the property and Lawrence was gone. Matthews said the shed had been cleared out and police were informed that Lawrence had “moved off the property.”

“We know now that Joan was moved 600 metres away to a nearby abandoned van where she lived among other derelict vehicles for another two months before she met her end on that property,” Matthews said.

No charges have been laid in connection with the deaths of the four seniors but police say they believe someone who worked for the retirement homes in the past may have information about the disappearances.

Police urged anyone with information about the case to come forward and speak to investigators.