03/26/2013 06:20 EDT | Updated 05/26/2013 05:12 EDT

How police search for missing children decades later

Police have been searching for Michael Dunahee for more than 22 years, since the then four-year-old boy disappeared during a family outing in Victoria, B.C. While the missing child is believed to have grown into a 26-year-old man, police investigative techniques have also matured, making the Victoria Police Department hopeful that Michael's case can still be resolved.

On March 24, 1991, Michael disappeared from a school playground while with his parents and younger sister.

The disappearance — labelled an abduction the following day — sparked one of the largest child abduction investigations in Canadian history, involving nearly 100 police officers from the region and across B.C.'s Lower Mainland.

Almost two decades ago, Michael's case went what would be considered viral by today's standards:

- Two months after the kidnapping, 35 Canadian cities plastered missing-child posters with Michael's information at bus stops and other public spaces.

- America's Most Wanted, a popular U.S. true crime program, appealed to the public for help and received reports of some 200 sightings across the country.

- Every household in B.C.'s Lower Mainland received a missing-child poster.

Social media savvy investigations

Twenty-two years later, Michael remains missing. But now investigators are becoming more savvy with new technologies, Sgt. Lana Prosper, who runs the RCMP's National Centre for Missing Persons and Unidentified Remains, told CBC News.

"A lot of the time [investigators] try to think outside of the box as far as they can to see what else is out there or what new technology could help them bring closure," she said.

The centre offers a computerized photo-age progression service for children who have been missing for at least two years.

Based on the newest photos of the child and photos of their biological family members, a trained forensic artist creates an image showing what the child would look like today. A missing person website created for Michael shows photos of what he would look like at five, 10, 15, 17 and 26 years old.

Prosper said investigators not only use these photos to update flyers and websites, but also for online sleuthing. Tips and searches using images can bring up social media accounts like Facebook and Twitter with photos of the missing child, she said.

A few years ago, investigators located a Canadian child who had been missing for 15 years when they discovered photos on a social media account of a person who looked like an artist's rendering of the missing child, she said.

The person had been kidnapped at such a young age and removed from the former environment to such a degree that this person never realized there had an abduction. The name of the person cannot be released because the case involved a minor.

Investigators also search for photos being posted by the kidnapper.

Signy Arnason, the associate executive director for the Canadian Centre for Child Protection, said usually those cases involve children kidnapped by a parent rather than a stranger. Though she recognizes the importance of online sleuthing in missing children cases.

"Most people — almost all people — have some type of technological imprint on the internet," she said. "You never know what you're going to find."

Online presence is crucial

The centre works to keep missing children cases in the public eye, she said, and helped Michael's parents create a website to serve as a home base for all the information about his case.

"It's the most well-known case in Canadian history in terms of a missing child," she said. Over the course of the investigation, police have looked into more than 11,000 tips.

"Somebody knows what has happened to this boy, so we want to ensure that we are keeping that out in the public forum," said Arnason.

She said she hopes the website and any other publicity will help people come forward and reports tips or sightings, eventually leading to a much-needed break in the cold case.

Sgt. Prosper said investigators spend a lot of energy using social networking sites to reach potential tipsters.

When a new missing-child report emerges, or an older case like Michael's is revisited on its anniversary, social media can bring the story to someone who may have information, but is unaware of the situation, like a tourist who was passing through the area at the time, but did not see the local news the next day.

Keeping hope alive

Michael's parents, Crystal and Bruce Dunahee, both believe their son is still alive. Crystal calls it "mother's intuition."

"I'm just wondering, you know, do I have any grandchildren, or where he is, or what's going on with his life," said his father.

Propser said she thinks keeping hope alive is important for parents of children who have been missing for long periods of time and she doesn't view it as a negative thing.

"A lot of the time, as investigators, that's what we need too," said Prosper. "We need to know that the parents are hopeful. It keeps us motivated."