A scuba diver wiped away the algae on a submerged car’s license plate and exclaimed: “It’s them!” That discovery of two long-missing American teens’ apparent remains was the latest tragic find for a subculture of YouTube sleuths.Among the platform’s viral hits scoring billions of views is a niche of YouTubers who use sonar devices to search waterways for vehicles linked to US missing persons cases — and the bones they may hold.That formula was central to revelations this week in a 21-year-old mystery in the southern state of Tennessee, one of a series of cold cases unravelled with the revenue generated by the clicks that these operations’ clips generate.Experts note the larger boom in Internet sleuthing has had a mixed impact, with high-profile misfires, and the temptation for viral content, but in some key instances the crowd’s contribution has been critical.Teens Erin Foster and Jeremy Bechtel disappeared in April 2000 from their small central Tennessee town of Sparta, leaving family and friends to hope they had just run away to start a new life.But 42-year-old Jeremy Sides — a scuba diver whose YouTube channel “Exploring with Nug” focuses on finding missing property and people — posted a video on December 4 that has since been viewed some 1.4 millions times and which seems to have resolved the mystery.”Once I confirmed it was the tag (license plate)…it was just a wave: This is going to be over, they get to go home, their families have answers,” he told AFP of his dive to find the car in Tennessee’s Calfkiller River.This was the second time in about a month that Sides had been instrumental in seemingly closing a case — the first was finding a car linked to a woman missing since 2005 in the Tennessee town of Oakridge.Authorities in Sparta were on Friday still working to confirm the identities of the remains found by Sides, but local police said they believed they belonged to the missing teens.’Nobody saw them crash’Another group of YouTubers, Chaos Divers, said they have located the remains of seven missing people in the past two months in an intense push that has seen them travel some 8,000 miles (nearly 12,900 kilometres) in the United States.The work unleashes intense emotions, especially breaking the news to families who lived in the limbo of not knowing what happened to their sons, wives or brothers.”It’s a heartbreaking, gut-wrenching feeling that you never want to give up. Because you are telling them and you’re watching the tears roll down their face, but you’re watching this weight lift off their shoulders,” said 38-year-old Lindsay Bussick, who is Chaos Divers founder Jacob Grubbs’ partner in the operation.Illinois-residents Bussick and Grubbs said their work was not simply an effort to get the clicks on YouTube that determine how much of a financial return a video may generate.”I’m sorry that I have to bring this content like this to be able to help defend the next family,” said Grubbs, a 38-year-old former coal miner.”But this is a way that we have figured out to be able to fund the help for another family,” he added.Adam Scott Wandt, an assistant professor of public policy at John Jay College of Criminal Justice in New York City, said untrained “true-crime armchair sleuths” and their efforts have become a cultural phenomenon in the past decade.But the results have varied greatly. He noted that some people pointed toward the social media swirl around slain US road-tripper Gabby Petito as helping police find her body this year.At the same time, Internet sleuths tarred an innocent college student in the fear-stoked effort to find the attackers who set off homemade bombs that killed three at the 2013 Boston Marathon.”The public is getting better at it, but it still can be very self-serving,” added Wandt, noting the temptation for seeking clicks. “But I’m definitely seeing more positive use over time.”Working as a complement to police, rather than shovelling tips and theories at investigators, is one way that freelancers seem to have found a role.Police in the Sparta case said they had heard Sides was investigating in their area, but after noting he wasn’t searching in the right place, they offered some advice on where to look.The bittersweet discovery followed days later.”I ended my search in that river in town, and that’s where I found them. It looks like a simple car accident,” Sides told AFP.”They just went off the road and nobody saw them crash. So sadly that’s where they sat for 20 years until I came along,” he added.