When the trail goes cold

At any given time across Canada there are hundreds of reports of missing people and police investigations that have gone cold. There are also mysteries around unidentified human remains that take police into one investigative direction and then another, only to land at dead ends.

With advances in technology and forensic science, a lot has changed for police working on these cases. But there are some aspects of the investigations that remain rooted in all police work.

"It's the old principle of try, try, try again," says RCMP Insp. Carole Bird, Officer in Charge at the National Centre for Missing Persons and Unidentified Remains. "We have to keep at it."

In most circumstances police rely on the public to help with their investigations. The following examples, from several jurisdictions across the country, are some of those cases.

More: Tracking missing people in the 21st century