Myrtle Beach Police Department has opened an investigation into a missing person identified as Jason Callahan after efforts on a social media page to identify "Grateful Doe," a young man who was killed in a car accident around the time Callahan went missing in 1995. Court4esy

IN June 1995, 18-year-old Jason Callahan left home in Myrtle Beach, South Carolina to follow the Grateful Dead on tour. He never returned.

Now amateur sleuths on Facebook appear to have solved his case.

His mother reached out after coming across the cold case page set up on the social network for “Grateful Doe”, an unidentified young man in a brand-new Grateful Dead T-shirt who died in a car accident in Virginia that same month.

He was a passenger in a Volkswagen van that veered off the road and hit two pine trees, killing both him and the driver. It was thought he was a hitchhiker, because none of the driver’s family had any idea who he was.

A short note was found in his pocket, written to “Jason” and signed “Caroline T. and Caroline O.”

His injuries were so traumatic that the police composite sketch was not thought to be very accurate. In 2012, a new computer-created version based on autopsy photos was made, and that’s when the Facebook page appeared.

“If someone did not have a reason to believe their friend or family member was dead, they probably would not have recognised him from the old sketch,” the page read. “This page exists to use social media to spread this image to someone who knew him, so that he may have his real name and identity back, and the intriguing case that has captured the hearts of so many can finally be solved.”

Then 63-year-old Margaretta Evans posted a message. “This is my son Jason Callahan,” she wrote. “I’ve been looking for him for all this time with no luck. Today, my other son saw this FB page, and after all the years of praying for him to just call me or come home...”

She supplied photos of her son to the community, which has almost 10,000 likes, and DNA tests are now underway to confirm whether Grateful Doe really is Jason.

The Grateful Doe Facebook page is just one of millions dedicated to cold cases. Some look at individual mysteries from the past, while others collate stories around a theme — murders, missing persons, the unexplained. There are internet forums, websites and Twitter accounts focused on getting to the bottom of inexplicable cases, where users scour satellite images for clues on the disappearance of flight MH370, or trade theories on the connection between millionaire Robert Durst and three murders, currently the subject of popular TV show The Jinx.

The popular WebSleuths site last month identified a girl fatally shot in a Livingston County cornfield in 1979 as Tammy Jo Alexander, a teenager who had gone missing from Florida, and uncovered online videos and thousands of deleted Twitter posts that revealed missing Michigan medic Teleka Patrick’s apparent obsession with a local minister.

Reddit is the internet detective’s dream, offering subreddits including Without A Trace, Unsolved Murders and Serial Killers. The wildly successful true crime podcast Serial spawned a monster on the social network, with millions offans endlessly speculating on the case, conducting forensic online research and even visiting the murder scene.

This is where things get a little uncomfortable. Victim Hae Min Lee’s family pleaded with the sleuths not to dredge up their pain, with her brother posting on Reddit: “TO ME ITS REAL LIFE. To you listeners, its another murder mystery, crime drama, another episode of CSI. You weren’t there to see your mom crying every night, having a heartattck when she got the new that the body was found, and going to court almost everyday for a year seeing your mom weeping, crying and fainting. You don’t know what we went through. Especially to those who are demanding our family response and having a meetup... you guys are disgusting. Shame on you. I pray that you don’t have to go through what we went through and have your story blasted to 5mil listeners.”

Even the family of convicted Adnan Syed, who wanted his case to be reopened to prove him innocent, told The Guardian they found it difficult reading “toxic” posts about the case on Reddit.

In the US, the 1996 case of murdered six-year-old JonBenet Ramsey led to what her parents John and Patsy called “the first cyberspace lynching”, a new form of witch-hunting and vigilantism that tore into almost everyone connected to the case, and contributed to the shutdown of the Justice Watch website. After the Boston bombings, over-excited Reddit detectives had to apologise for pinning blame on the wrong man.

“We live in a more interconnected world than we could ever have imagined, and a very transient world where people move around a lot,” Peter Price, a spokesperson for Crimestoppers Australia, told news.com.au. “The greater the opportunity to post pictures of people or items and get more eyeballs on them, the better.”

But he added: “We want people to help law enforcement, not be law enforcement. We don’t want them to be detectives. If people have potentially real information they should supply it to police and Crimestoppers through the proper channels.”

He warned against the narcissistic side of the endeavour. This isn’t about having a glorified sense of having solved a crime. This is real life.

“The driver should be, ‘I’ve helped the police solve a crime’,” said Mr Price. “It’s about helping the community.”

And people are doing that. Crimestoppers gets 5000 calls a month and our community police services have Eyewatch pages with thousands of likes. Detectives are crowdsourcing all over the page. And the CIA has just refocused on digital espionage.

“The police do media monitoring all the time,” said Mr Price. “There are more and more vendors of tech information that are about monitoring web chatter. It’s not all crime — it’s also marketing, brand protection and service delivery, of hotels or transport.”

But he admits the capacity for this online research is still “not great”. The authorities can’t look at millions of Facebook pages, or even close, and meanwhile gleeful internet investigators find their theories going viral overnight. In the case of JonBenet, one amateur detective got on television, while another gained a police interview over her paedophile ring theory, which was found to be riddled with holes.

On the Grateful Doe page, new puzzles are posted each day, and there is palpable emotion over the possible closure of the community’s namesake case.

“It’s so hard, in one way I’m hoping & praying it’s him & in another way I’m hoping & praying it’s not,” wrote one user. “I feel so much sadness for his mom right now.”

Others said it felt good to finally know that, if Jason is the dead man, he was happy and loved for his short life.

“Rest In Peace Jason, our community has brought you home to rest,” came another comment. “The grateful dead, of sorts.”