When a young British man disappeared while vacationing on the Spanish island of Tenerife in mid-June, a familiar routine unfolded: search and rescue workers combing through the landscape, regular updates from tearful family members, a steady drumbeat of unconfirmed reports that he had been spotted.
And soon after, they were joined by another increasingly common feature of disappearances: online sleuths who are certain that they can do what the police have not yet done and solve the case.
This weekend, the Spanish authorities called off their search for Jay Slater, a 19-year-old apprentice bricklayer from England who was visiting Tenerife, a popular vacation destination. But even after the 14-day search officially ended, conspiracies and other theories have continued to spread online.
“There’s a small minority that believes and engages with these things,” said Aleksandra Cichocka, a professor of political psychology at the University of Kent. “But they can be really disturbing to the family and the whole process of the investigation.”
Mr. Slater attended a music festival on the island with a friend, according to a statement from his mother, Debbie Duncan, through the missing persons organization LBT Global. On the festival’s final night, Mr. Slater left with two people he had met at the event to go to their apartment in a more secluded part of the island, according to Lucy Law, a friend with him who provided details in an online fund-raising page for his family.
The next morning, on June 17, Ms. Law said Mr. Slater told her on a phone call that he was lost in the mountains, thirsty and running out of phone battery. He called another friend, who told the British news media that Mr. Slater had decided to go down a “little drop” beside a road. That morning was the last time anyone heard from him.
For nearly two weeks, the authorities in Tenerife scoured the area around Masca, a mountainous village near a nature reserve, with help from specialist search dogs. Temperatures on the island, off the northwest coast of Africa, have hovered around 27 degrees Celsius (82 degrees Fahrenheit).
Spain’s Civil Guard has confirmed few details about the case. Over the weekend, before calling off the search, they asked for volunteers with experience on rough terrain, British news media reported.
The search has unfolded against a frenzied backdrop of attention from British news outlets and impromptu groups of conspiracy thinkers. In Facebook groups, one of which has more than 600,000 members, watchers traced Mr. Slater’s last known steps and searched livestreams of Tenerife, hoping for a sign of him. Some people — from climbing influencers to crime investigators — traveled to the island to aid the search.
“We are aware of the conspiracy theories and speculation on social media and some websites, and can only describe this as vile,” Ms. Duncan said. “The negative comments are extremely distressing to our family.”
Still, Ms. Duncan, who did not immediately respond to requests for comment, and some friends of the teenager have reportedly welcomed some offers of help from TikTok searchers. But the flood of attention has also included many unfounded theories and conspiracies, and Mr. Slater’s family told British news media that they feared the online speculation had hindered the investigation.
Administrators of one group who said they were in touch with the family criticized the spread of conspiracies on platforms like TikTok.
Mr. Slater’s employer, PH Build Group, said last week on Facebook that it had received harassing emails: “Everyone may have their own theories and feelings but to publicly post them knowing you are going hurt people is just cruel.”
The authorities in Tenerife on Tuesday confirmed in an email that while the official search had ended, the investigation remained open until they determined what happened to Mr. Slater.
“We just want to find him,” Ms. Duncan said.
Conspiracies can generate a lot of attention and engagement on social media, Ms. Cichocka said. Sharing them, she said, can make people feel as if they’re creating order in a chaotic situation, even one with which they have no real involvement.
“It’s a coping mechanism that helps people deal with an unmanageable reality,” Ms. Cichocka said.
In the grand scheme, the number of people who are creating and sharing these theories is often small. But because of the speed with which misinformation spreads, small pockets can have immense influence.
Other cases have also drawn intense online speculation. The family of Nicola Bulley, a 45-year-old woman from Lancashire, England, who died in 2023 after falling into a river, criticized the rampant theories on social media after her death, even after a coroner’s report found no third-party involvement. Ms. Bulley’s family asked the public “to look at the facts, the evidence,” and to ignore any amateur opinions, adding that people should be “mindful of the impact words bring.”
Earlier this month, Greek authorities found the body of Dr. Michael Mosley, a British medical journalist and documentary maker who the authorities said likely died of natural causes. His disappearance prompted an intensive search on the Greek island of Symi.