After making a plea for information this past summer, Ontario Provincial Police say they have received a significant amount of tips in the case of four seniors who went missing more than two decades ago in Muskoka.

“As a result of the press conference I think they realized police didn’t have this information and we just got people coming forward – people from all the province calling and providing us information we did not have that was very beneficial for the investigation,” said Detective Inspector Rob Matthews, who has been involved in the investigation since the beginning.

In July, police held a press conference updating the historical missing persons case that is now a homicide investigation. Matthews said new tips has allowed police to move the investigation forward.

“Those tips that came forward – some of them involved individuals that had a connection to the former retirement homes or properties,” he said.

Joan Lawrence, who was 77 years old at the time, disappeared in 1998. Between 1997 and 1999, 91-year-old John Semple, 72-year-old John Crofts and 73-year-old Ralph Grant also disappeared.

Despite extensive searches, no human remains have ever been recovered but all four are believed to be dead.

The seniors were residents at the Fern Glen Manor and Cedar Pines which were owned and operated by members of the Laan family. Police won’t call the family suspects in the case, but do say family members have never cooperated with the investigation.

At this point, the owners are considered people of interest.

“We’re missing a significant piece because the family are not cooperating,” said Matthews. “There is two sides to every story and I would like nothing more than them to come forward with their lawyers and provide us a statement.”

The OPP have said the two retirement homes took in vulnerable seniors who no longer had contact with their families in the late '90s, and police regularly received complaints and concerns over how the occupants were treated.

Investigators are not providing any further insight on any information they’ve recently received, but are optimistic they will eventually bring closure to the families of the seniors.

In the meantime, investigators continue to appeal to anyone with information about the case to come forward.

-with files from The Canadian Press